Answer:
22
Step-by-step explanation:
28+7+6+3=44
44/2 or 44*1/2 = 22
A boat covers 25 km upstream and 44 km downstream in t hours. Also, it covers 15 km upstream and 22 km downstream in 5 hours. Find the speed of the boat in still water and that of the stream.
9514 1404 393
Answer:
boat speed: (7t -95)/(6t² -110t +500)
stream speed: (37t -345)/(6t² -110t +500)
Step-by-step explanation:
The relation between time, speed, and distance is ...
time = distance/speed
The boat speed (b) is added to the stream speed (s) going downstream. The stream speed is subtracted going upstream. The given relations tell us ...
25/(b-s) +44/(b+s) = t
15/(b-s) +22/(b+s) = 5
This gives us 2 equations in 3 unknowns, so we can only provide a solution in terms of one of the unknowns. Since we are asked for the speeds, they will be provided in terms of t.
Subtracting the first equation from 2 times the second gives ...
2(15/(b-s) +22/(b+s)) -(25/(b-s) +44/(b+s)) = 2(5) -(t)
5/(b-s) = 10 -t
5/(10 -t) = b -s
Substituting for b-s in the second equation gives ...
15/(5/(10-t)) +22/(b+s) = 5
30 -3t +22/(b+s) = 5
22/(b+s) = 3t -25
22/(3t -25) = b+s
Adding the equations for the sum and difference of speeds, we get ...
(b-s) +(b+s) = 5/(10-t) +22/(3t -25)
2b = (5(3t -25) +22(10 -t))/((10-t)(3t-25)) = (95 -7t)/((10-t)(3t-25))
b = (7t -95)/(6t² -110t +500)
Subtracting the equations for sum and difference of speeds, we get ...
(b+s) -(b-s) = 22/(3t -25) -5/(10 -t)
2s = (22(10-t) -5(3t -25))/((10-t)(3t-25))
s = (37t -345)/(6t² -110t +500)
__
The speed of the boat in still water is (7t -95)/(6t² -110t +500) km/h.
The speed of the stream is (37t -345)/(6t² -110t +500) km/h.
__
Note that these solutions only make sense for values of t between 25/3 and 345/37, approximately 8.33 < t < 9.32. For t=9 hours, the boat speed is 8 km/h and the stream speed is 3 km/h.
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A textbook company states that the average time a student needs to take a quiz from its book is 30 minutes with a standard deviation of 3 minutes. A teacher using the book is not sure that this is correct for her classes and wants to check. She collects data on 10 random students and finds that the average time to take the quiz was only 25 minutes. As a result, the teacher performs a two-tailed hypothesis test with a significance level of 5%. Which conclusion is valid based on the results of the test
Answer:
We conclude that her students, on average, do not take 30 minutes on the quiz, contrary to what the textbook company states.
Step-by-step explanation:
We are given;
Population mean; μ = 30 minutes
Population standard deviation; σ = 3 minutes
Sample size; n = 10
Sample mean; x¯ = 25
Significance level = 5% = 0.05
Let's define the hypotheses;
Null hypothesis; H0: μ = 30
Alternative hypothesis: Ha: μ ≠ 30
Let's find the test statistic;
z = (x¯ - μ)/(σ/√n)
z = (25 - 30)/(3/√10)
z = -5.27
From online p-value from z-score calculator attached using, z = -5.27, significance level = 0.05, two tailed hypothesis, we have;
p < 0.00001
This is less than the significance level, and so we will reject the null hypothesis and conclude that Her students, on average, do not take 30 minutes on the quiz, contrary to what the textbook company stated.
Answer:
A. Her students, on average, do not take 30 minutes on the quiz, contrary to what the textbook company stated.
Robin, Ashley, Joy, and Christina collected 156 acorns to make fall decorations. Robin collected three times as many acorns as Ashley.Christina
has 12 more acorns than Robin. Ashley and Joy collected the same number of acorns.
How many acorns did Ashley collect?
PLEASE HELP
Answer:12
Step-by-step explanation:
PLEASE HELP ME ILL GIVE 70 POINTS AND MARK BRAINLIEST
Answer:
7: 28x+4 6:20x+2
Robert claims that his dog can do single-digit multiplication. He shows the dog 8 cards with simple multiplication problems that are either correct or incorrect. The dog correctly identifies the correctness of the card 5 times out of 8. If the dog were simply guessing, how many would the dog be expected to get correct? (1 point) Group of answer choices 5 8 13 4
Answer: Theorically it would be 4
Answer:
4
Step-by-step explanation:
Well since he has a 50% of getting it right, we use 50% of 8 which would be 4
also how does robert have such a smart dog-
Madeline has 2 times the number of games as Paulo. Paulo has 4 more games than Tyler. If Tyler has 9 games, how many games are there among the 3 friends?
how would I word that it is being doubled in size?
The question is how did D get to E.
Answer:
It doubled up is what you could say
How can I Solve this problem Solve. for g.
18 = 3g
g
Answer:
[tex]g = 6[/tex]
Step-by-step explanation:
1) Diving both sides by 3.
[tex] \frac{18}{3} = g[/tex]
2) Simplify 18/3 to 6.
[tex]6 = g[/tex]
3) Switch sides.
[tex]g = 6[/tex]
Therefor, the answer is g = 6.
please help !
A local paintball facility charges $30 to play plus $0.25 per paintball pellet used. Elijah plans on playing paintball and has $60 to spend at the facility. Which equation can be used to determine p, the number of paintball pellets he can use if he spends exactly $60?
A. 30 + 0.25p = 60
B. 30 + 0.25 = 60p
C. 30p + 0.25 = 60
D. 30 − 0.25p = 60
Step-by-step explanation:
Hello! I believe the answer is A. 30+0.25p=60.
Elijah has to pay a facility charge which is 30$. So we can go ahead and write that down! He has 60$ to spend, but he has to pay $0.25 per paintball. So we write that as 30+0.25p=60!! If you have any questions comment doen below!
Answer:i think it A to
Step-by-step explanation: it is the only one correct
Apply the problem-solving techniques to solve the following
problem.
Population decrease In 1990, a rural area had 1200 bird
species. If species of birds are becoming extinct at the rate of
1.5% per decade (10 years), how many bird species will there be
left in the
year
2020?
Answer:
By 2020, there will be 1,147 species of birds left
Step-by-step explanation:
The general model for an exponential decrease is;
y = I(1 - r)^t
where in this case;
y is the number of bird species at a particular decade from the initial
I is the number of birds initially at 1990
r is the decrease percentage which is 1.5% per decade ; 1.5% = 1.5/100 = 0.015
t in this case will be the number of decades after the initial
Mathematically, a decade is 10 years
The difference between 2020 and 1990 is 30
The number of decades in 30 years is 30/10 = 3
so t will be 3 here
Substituting these values into the equation, we have
y = 1200(1-0.015)^3
y = 1200(0.985)^3 = 1,146.8
To the nearest whole number, this is 1,147
What is the median test score of the data shown in the box plot?
Answer:
75
Step-by-step explanation:
Note the location of the vertical line inside the box. This locates the median. Looking carefully, we see that this line hovers over 75 in the list of test scores.
The median is 75. Look up "median" and "box plot" if you need more information.
Substitution
x+5y=13, 4x+7y=0
PLEASE HELP MEE<3
Step-by-step explanation:
x+5Y=13...... 1
4x +7y=0..... 2
from eqn 1
x =13-5y
substitute into eqn 2
[tex]4(13 - 5y) + 7y = 0[/tex]
52-20y +7y=0
52-13y=0
52=13y
y=52÷13
y=4
substitute Y into eqn 2
x +5y=13
x + 5(4)= 13
x+ 20=13
x=13-20
x=-7
Which side lengths will NOT form a triangle? *
8.5 in., 12.5 in., 16 in.
5.5 in., 7.5 in., 13 in.
6 in., 8 in., 8 in.
11 in., 10 in., 9 in.
Answer:
The 6in, 8in, 8in one.
Step-by-step explanation:
Guys please could you answer this question I'm unable to solve this assignment
guyssss ANYONEEE PLSSS!!!!!I NEED HELP LIKE ACTUALLY
Answer:
infinite number of solutions
find the measure of each interior and exterior angles of a regular polygon with 48 sides
Answer:
172.5
may this will help you
A and b are positive integers and a-b=2. Evaluate the following:
27^1/3b/9^1/2a
thank you very much
Answer:
Answer: 1/9
Step-by-step explanation:
(27^1/3 = 3
9^1/2 = 3
3^b
====
3^a
3^(b - a)
3^-2 = 1/9
1/9
Workout the median of 83,73,76,72,75,86,79,76
Answer:
76
Step-by-step explanation:
Put the numbers in order from least to greatest.
72, 73, 75, 76, 76, 79, 83, 86
Then, cross off each number at each end until you reach the one in the middle. Which, since they are the same, is 76.
hi. how to give brainliest :-)..........
Answer:
you have to be above ambitious to unlock brainiest answer
Step-by-step explanation:
Answer:
You got wait for 2 people to answer to this then at the bottom right theirs a crown click n that’s how u give brainliest
Step-by-step explanation:
plz answer the question and explain how you got the answer
I don't know what the answer is. Please Help
Answer:
D.
Step-by-step explanation:
Hope this helps
~R3V0
David made a batch of 5 liters of blue liquid everyday for 3 days how many milliliters of blue liquid did he make in all
Answer: 15000 millimeters
Step-by-step explanation:
Since David David made a batch of 5 liters of blue liquid everyday. The number of liters that'll be made for 3 days will be:
= 5 liters × 3
= 15 liters
We should note that 1000 millimeters = 1 liter. Therefore, 15 liters will be converted to millimeters which will be:
= 15 × 1000
= 15000 millimeters
15 chocolate were distributed between raju and sanju in the ratio 2:3 . How many chocolates did raju receive?
Answer:
6chocolates
Step-by-step explanation:
Given
The total number of chocolate = 15chocolates
If it is divide into ratio 2:3
total ratio = 2+3
Total ratio = 5
Number of chocolate raju receives = 2/5 * 15
Number of chocolate raju receives = 2 * 3
Number of chocolate raju receives = 6chocolates
The number of chocolates that Raju received are; 6 chocolates
ProportionWe are told that;
Number of chocolates distributed = 15
Ratio of sharing between Raju and sanju = 2:3
Thus, fraction to be received by both of them are;
For Raju = 2/(2 + 3) = 2/5For Sanju = 3/(2 + 3) = 3/5Thus;
Amount of chocolates for Rajus = 2/5 × 15 = 6
In conclusion, Raju received 6 chocolates.
Read more about proportion at; https://brainly.com/question/1781657
How many sides does a polygon have?
Answer:
it can have any about 3 and up as long as it is a 2d shape and it has to have straight lines
Answer:
They all vary. All a polygon needs is straight sides, two dimensions, and equal length sides.
Step-by-step explanation:
Hope this helps!
EAR is rotated 180° about the origin.
plsss help
Answer:
rotating ΔEAR 180° inside the right angle parallelogram circumscribed by.
original coordinates:
A (-6, 4)
R (-2, 2)
E (-5, -6)
post rotation coordinates:
A (-2, -6)R (-6, -4)E (-3, 4). A movie company sells DVDs on line. Each
DVD costs $9.95. No matter how many you
order, the shipping charge is $3.59. Your most
recent order came to a total of $33.44.
Please help on all questions in picture
Multiply by cost of a dvd by the number of dvds bought ( x) and add the shipping charge.
A) 33.44 = 9.95x + 3.59
Subtract 3.59 from both sides.
29.85 = 9.95x
Divide both sides by 9.95
X = 29.85/9.95
X = 3
They bought 3 dvds.
B) 33.49-3.59 = 29.85
29.85/9.95 = 3
C) the steps were the same but solving arithmetic you didn’t have to do steps on both sides of an equation.
A group of friends wants to go to the amusement park. They have no more than $125 to spend on parking and admission. Parking is $13,and tickets cost $12.50 per person, including tax. What is the maximum number of people who can go to the amusement park?
Answer:
8
Step-by-step explanation:
Let x be the number of people
12.5x + 13 < 125
x < 8.96
Max number of x is 8
if u put any links I will report
Answer:
72% increase
Step-by-step explanation:
688-400= 288 increase
288/400= 0.72
0.72x100=
72% increase
What is the surface area of the cylinder with height 6 in and radius 7 in? Round your answer to the nearest thousandth.
Answer:
571.77
Step-by-step explanation: I might be wrong so don't really trust me