Question

The ratio of boys to girls in a class is 2:3. If there are 18 girls in the class, what is the probability of a boy being in the class, P(boy)? SHOW WORK to verify your choice.

Answer 1

0.4

Explanation:

If the ratio of boys to girls in a class is 2:3, then

• there are 2x boys;
• there are 3x girls.

If there are 18 girls in the class, then

`3x=18\\ \\x=6`

Thus, there are

• 
  `2\cdot 6=12` boys;
• 
  `3\cdot 6=18` girls;
• 
  `12+18=30` students in total.

The probability of a boy being in the class is

`P=(12)/(30)=(2)/(5)=0.4`