Question

125 freshman, 85 passed the english test, 95 passed statistics test, 15 failed both what is the probability that they passed both

Answer 1

0.56

Explanation:

125 in total.

Let x be the number of those who passed both tests.

• 85 passed English, then 85-x passed only English;
• 95 passed statistics, then 95-x passed only statistics;
• 15 failed both.

Thus,

x+(85-x)+(95-x)+15=125,

195-x=125,

x=70.

Thus, the probability that they passed both tests is

`Pr=(70)/(125)=(14)/(25)=0.56.`