Question

A movie theater complex gave a poll as viewers exited from two theaters showing the same film. They had a 20% response rate from the people in theater A and a 30% response rate from the people in theater B. There were 800 people in total in theaters A and B.

Part A:​ It was estimated that an equal number of people from each theater responded to the poll. If this was the case, how many people in total would have been in theater A?

Part B:​ In reality, 440 people were in theater A and 360 people were in theater B. What was the total response rate for the poll? Express your answer as a percentage.

Answer 1

Let´s define the variables:

x = number of people in theater A

y = number of people in theater B

We know that a 20% (or 0.2 in decimal form) of the people in theater A answered the survey, then the number of people from theater A that answered the survey is: Na = 0.2*x

We know that a 30% (or 0.3 in decimal form) of the people in theater B answered the survey, then the number of people from theater B that answered the survey is: Nb = 0.3*y

There where 800 people in total (counting from the two theatres)

Then x + y = 800.

A) In this case we have:

Na = Nb

this means that:

0.2*x = 0.3*y

and we also have the equation:

x + y = 800

To solve this, we need to isolate one variable in one of the equations, i will isolate x in the second equation:

x = 800 - y

And now we can replace this in the other equation to get:

0.2*(800 - y) = 0.3*y

We need to solve this for y:

160 - 0.2*y = 0.3*y

160 = 0.3*y + 0.2*y = 0.5*y

160/0.5 = y = 320

Then there where 320 people in theater B, and:

x + y = 800

x + 320 = 800

x = 800 - 320 = 480

There where 480 people in theather A.

B) Now we have:

x = 440

y = 360

then:

Na = 0.2*440 = 88

In theater A, 88 people answered the survey.

Nb = 0.3*360 = 108

In theater B, 108 people answered the survey.

In total, 88 + 108 = 196 people answered the survey.