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4 years ago

It takes 32 minutes for 3 people to paint 4 walls. How many minutes does it take 4 people to paint 7 walls?

Mathematics

1 answer:

vampirchik [111]4 years ago

6 0

Answer:

Step-by-step explanation:

Assuming each person gets the same amount of work done, each wall in the first scenario takes 8 minutes to paint. If 3 people paint 4 walls, then each person is painting 1 1/3 of a wall. We can use that to find out how long it takes one person to paint 1 1/3 walls:

$\frac{8min}{wall}*\frac{4}{3}walls=\frac{32}{3}min$ . Interpreting that, it takes each person 10 2/3 minutes to paint 1 1/3 walls.

If 4 people paint 7 walls, that means that each person is painting 7/4 walls, or 1.75 walls each. Using the fact that it takes 10.66666 minutes to paint 1.33333 walls, we can find out how many minutes it will take to paint 1.75 walls:

$\frac{10.6666}{1.33333}=\frac{x}{1.75}$ Cross multiply to get

18.666655 = 1.3333x so

x = 14.000 minutes

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If (h + h) · (h. h) = 16, find the value of h.<br> — HELP ME PLEASEEEE

yKpoI14uk [10]

Answer:

h = 2

Step-by-step explanation:

I'm assuming your periods are multiplication signs.

(h + h) X (h X h) = 16

When adding two variables like the first set of parentheses, it would become 2h. When multiplying two like variables, you add the exponents. h is the same as writing h¹. So h¹ x h¹ gives you the answer of h².

So now your equation would look like:

2h X h² = 16

As above, when you multiply two like variables you would add the exponents. Also if any number are in front of the variable you would multiply those numbers. So you have 2h¹ x 1h² and that would be 2h³. If it had been

2h¹ x 2h², your answer would have been 4h³.

But so far you have 2h¹ x 1h² = 16

2h³ = 16

Dividing both sides by 2 you get

h³ = 8

To find h you have to take the cubed root of 8. What number multiplied by itself 3 times gives you 8? 2 x 2 x 2 = 8 2 x 2 = 4 and x 2 = 8.

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3 years ago

The increasing annual cost (including tuition, room, board, books, and fees) to attend college has been widely discussed (Time).

NeX [460]

Answer:

(a) PRIVATE COLLEGES

Sample mean is $42.5 thousand

Sample standard deviation is $6.65 thousand

PUBLIC COLLEGES

Sample mean is $22.3 thousand

Sample standard deviation is $4.34 thousand

(b) Point estimate is $20.2 thousand. The mean annual cost to attend private colleges ($42.5 thousand) is more than the mean annual cost to attend public colleges ($22.3 thousand)

(c) 95% confidence interval of the difference between the mean annual cost of attending private and public colleges is $19.2 thousand to $21.2 thousand

Step-by-step explanation:

(a) PRIVATE COLLEGES

Sample mean = Total cost ÷ number of colleges = (51.8+42.2+45+34.3+44+29.6+46.8+36.8+51.5+43) ÷ 10 = 425 ÷ 10 = $42.5 thousand

Sample standard deviation = sqrt[summation (cost - sample mean)^2 ÷ number of colleges] = sqrt([(51.8-42.5)^2 + (42.2-42.5)^2 + (45-42.5)^2 + (34.3-42.5)^2 + (44-42.5)^2 + (29.6-42.5)^2 + (36.8-42.5)^2 + (51.5-42.5)^2 + (43-42.5)^2] ÷ 10) = sqrt (44.24) = $6.65 thousand

PUBLIC COLLEGES

Sample mean = (20.3+22+28.2+15.6+24.1+28.5+22.8+25.8+18.5+25.6+14.4+21.8) ÷ 12 = 267.6 ÷ 12 = $22.3 thousand

Sample standard deviation = sqrt([(20.3-22.3)^2 + (22-22.3)^2 + (28.2-22.3)^2 + (15.6-22.3)^2 + (24.1-22.3)^2 + (28.5-22.3)^2 + (22.8-22.3)^2 + (25.8-22.3)^2 + (18.5-22.3)^2 + (25.6-22.3)^2 + (14.4-22.3)^2 + (21.8-22.3)^2] ÷ 12) = sqrt (18.83) = $4.34 thousand

(b) Point estimate = mean annual cost of attending private colleges - mean annual cost of attending public colleges = $42.5 thousand - $22.3 thousand = $20.2 thousand.

This implies the the mean annual cost of attending private colleges is greater than the mean annual cost of attending public colleges

E = t×sd/√n

Mean = $42.5 - $22.3 = $20.2 thousand

sd = $6.65 - $4.34 = $2.31 thousand

n = 10+12 = 22

degree of freedom = 22-2 = 20

t-value corresponding to 20 degrees of freedom and 95% confidence level is 2.086

E = 2.086×$2.31/√22 = $1.0 thousand

Lower bound = Mean - E = $20.2 thousand - $1.0 thousand = $19.2 thousand

Upper bound = Mean + E = $20.2 thousand + $1.0 thousand = $21.2 thousand

95% confidence interval is $19.2 thousand to $21.2 thousand

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3 years ago

And another! Apparently you use the distributive property to remove the parentheses. .-.

Tju [1.3M]

6v+4w-4
Because you do -*-6v=positive 6v then -*-4w=positive 4w and then -*4=-4 and that takes care of the parenthesis
Basically you multiply the outside number or sign by all things inside the parenthesis
So in this problem you multiplied the negative sign by all the things inside the parenthesis

8 0

3 years ago