Step-by-step explanation:
40 days = 15 boys
1 day = 15/40 = 3/8
therefore,
30 days = 3/8 × 30
= 11.1/4 boys or 11.25boys
Answer: 17/20=0.85
Step-by-step explanation:
We have been given that the ages of students in a school are normally distributed with a mean of 15 years and a standard deviation of 2 years.
We are asked to find the percentage of students that are between 14 and 18 years old.
First of all, we will find z-score corresponding to 14 and 18 using z-score formula.




Similarly, we will find the z-score corresponding to 18.



Now we will find the probability of getting a z-score between
and
that is
.

Using normal distribution table, we will get:


Let us convert
into percentage.

Therefore, approximately
of the students are between 14 and 18 years old.
Answer:
$31.04
Step-by-step explanation: