Answer:
a) 0.3125
b) 45
Step-by-step explanation:
Remark
5 students own a smart phone
11 do not.
Part A
The probability of owning a smart phone is 5/16. Where did the 16 come from.? You must use a total for the sample. You can't choose someone without a smart phone and figure out the probability of doing that if you use 11 in the denominator.
So the answer is 5/16 = 0.3125
Part B
You have to set up a proportion for this.
x / 144 = 5/16
Notice where the 144 goes. It is across from 16. Both of them represent the total number of students. Multiply both sides by 144
x * 144 / 144 = 5 * 144/16
x = 720 / 16
x = 45
