Question

a group of people were asked if they had run a red light in the last year. 315 responded \yes\, and 385 responded
o\.
find the probability that if a person is chosen at random, they have run a red light in the last year.
give your answer as a reduced fraction or decimal rounded to four decimal places

Explanation:

Step1: Calculate total number of people

Total number of people = Number of "yes" + Number of "no"
$315 + 385=700$

Step2: Calculate probability

Probability formula is $P=\frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}}$. Here, favorable outcome is a person who said "yes".
$P=\frac{315}{700}$
Simplify the fraction: $\frac{315\div35}{700\div35}=\frac{9}{20}=0.45$

Answer:

$0.45$