Ask question

Ask question

All categories

Gelneren [198K]

3 years ago

8

there are 148 juniors and 272 seniors attending prom this year. if there must be three chaperones per 60 students, how many chap

erones are needed

1 answer:

valkas [14]3 years ago

3 0

21 chaperones are needed for 420 students.

Step-by-step explanation:

No. of juniors = 148

No. of seniors = 272

Total = 148+272 = 420 students

3 chaperones = 60 students

1 chaperone = $\frac{60}{3}=20\ students$

Ratio of chaperon to students = 1:20

Let,

x be the number of chaperons for 420 students.

Ration of chaperones to students = x:420

Using proportion

Ratio of chaperones to students :: Ratio of chaperons to students

$1:20::x:420$

Product of mean = Product of extreme

$20*x=420*1\\20x=420\\$

Dividing both sides by 20

$\frac{20x}{20}=\frac{420}{20}\\x=21$

21 chaperones are needed for 420 students.

Keywords: ratio, proportion

Learn more about ratios at:

#LearnwithBrainly

You might be interested in

Solve the equation by completing the square round to the nearest hundredth is necessary x^2-x-7=0

masha68 [24]

The answers are 3.19 or -2.19.

In order to complete the square, you must first get the constant to the other side of the equation. WE do that by adding 7 to both sides.

x^2 - x - 7 = 0

x^2 - x = 7

Now we must take half of the x coefficient (-1), which would be -.5. Then we square it and add it to both sides. This is the second step to any completing the square problem.

x^2 - x = 7

x^2 - x + .25 = 7.25

Now that we have done that, the left side will be a perfect square so that, we can factor it.

x^2 - x + .25 = 7.25

(x - .5)^2 = 7.25

After having done that, we can take the square root of both sides

(x - .5)^2 = 7.25

x - .5 = +/- $\sqrt{7.25}$

Now we can take the value of that square root and solve.

x - .5 = +/- $\sqrt{7.25}$

x - .5 = +/-2.69

x = .5 +/- 2.69

And with the + and - both there, we need to do both to get the two answers.

.5 + 2.69 = 3.19

.5 - 2.69 = -2.19

4 0

2 years ago

.<br> gbuhhubhhbuubbbubuubhbhhhbbubhbhbhubuhhbhbu

Tpy6a [65]

Question:

gbuhhubhhbuubbbubuubhbhhhbbubhbhbhubuhhbhbu

Answer:

yes

4 0

2 years ago

Question Help Suppose that the lifetimes of light bulbs are approximately normally distributed, with a mean of 5656 hours and a

koban [17]

Answer:

a)3.438% of the light bulbs will last more than 6262 hours.

b)11.31% of the light bulbs will last 5252 hours or less.

c) 23.655% of the light bulbs are going to last between 5858 and 6262 hours.

d) 0.12% of the light bulbs will last 4646 hours or less.

Step-by-step explanation:

Normally distributed problems can be solved by the z-score formula:

On a normaly distributed set with mean $\mu$ and standard deviation $\sigma$ , the z-score of a value X is given by:

$Z = \frac{X - \mu}{\sigma}$

After we find the value of Z, we look into the z-score table and find the equivalent p-value of this score. This is the probability that a score will be LOWER than the value of X.

In this problem, we have that:

The lifetimes of light bulbs are approximately normally distributed, with a mean of 5656 hours and a standard deviation of 333.3 hours.

So $\mu = 5656, \sigma = 333.3$

(a) What proportion of light bulbs will last more than 6262 hours?

The pvalue of the z-score of $X = 6262$ is the proportion of light bulbs that will last less than 6262. Subtracting 100% by this value, we find the proportion of light bulbs that will last more than 6262 hours.

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{6262 - 5656}{333.3}$

$Z = 1.82$

$Z = 1.81$ has a pvalue of .96562. This means that 96.562% of the light bulbs are going to last less than 6262 hours. So

$P = 100% - 96.562% = 3.438%$ of the light bulbs will last more than 6262 hours.

(b) What proportion of light bulbs will last 5252 hours or less?

This is the pvalue of the zscore of $X = 5252$

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{5252- 5656}{333.3}$

$Z = -1.21$

$Z = -1.21$ has a pvalue of .1131. This means that 11.31% of the light bulbs will last 5252 hours or less.

(c) What proportion of light bulbs will last between 5858 and 6262 hours?

This is the pvalue of the zscore of $X = 6262$ subtracted by the pvalue of the zscore $X = 5858$

For $X = 6262$ , we have that $Z = 1.81$ with a pvalue of .96562.

For X = 5858

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{5858- 5656}{333.3}$

$Z = 0.61$

$Z = 0.61$ has a pvalue of .72907.

So, the proportion of light bulbs that will last between 5858 and 6262 hours is

$P = .96562 - .72907 = .23655$

23.655% of the light bulbs are going to last between 5858 and 6262 hours.

(d) What is the probability that a randomly selected light bulb lasts less than 4646 hours?

This is the pvalue of the zscore of $X = 4646$

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{4646- 5656}{333.3}$

$Z = -3.03$

$Z = -3.03$ has a pvalue of .0012. This means that 0.12% of the light bulbs will last 4646 hours or less.

5 0

3 years ago

Oh 9i is a root of the polynomial function f(x), which of the following must also be a root of f(x)? A. -9i B. -1/9i C. 1/9i D.

kotegsom [21]

The best answer is A. The possible roots of this polynomial function 9i and -9i. It is possible that this polynomial function is a quadratic equation. It has a degree of two which means there are two roots and it is possible that the positive and negative value of 9i are its roots.

6 0

2 years ago

Read 2 more answers

Given the midpoint and one endpoint find the other endpoint. Endpoint (2,-9) Midpoint (-2,-1)

AfilCa [17]

Answer:

Step-by-step explanation:

(x + 2)/2 = -2

x + 2 = -4

x = -6

(y + (-9))/2 = -1

y - 9 = -2

y = 7

(-6, 7)

answer is C

6 0

2 years ago