Question

A survey was conducted and feedback collected where people rated two of the movies watched in a theater. The results are given below as joint relative frequencies. What is the total number of people who gave ratings, when $30$ people gave $5$ stars to movie A?

• A. $200$
• B. $500$
• C. $300$
• D. $100$

Answer 1

The correct option is A $200$

A joint relative frequency is the ratio of the frequency in a particular category and the total number of data values,
i.e., Joint relative frequency of the given category =
$\frac{\text{Frequency in that category}}{\text{Total number of data values}}$

Joint relative frequency for people who gave $5$ stars to movie $A=0.15$
Number of people who gave 5 stars to movie $A=30$ (given)

Joint relative frequency for people who gave $5$ stars to movie A $=\frac{\text{Number of people who gave 5 stars to movie A}}{\text{Total number of people}}$

Substituting them in the above formula, we get

$0.15=\frac{30}{\text{Total number of people}}$

Total number of people $=\frac{30}{0.15}$

$=200$