Question

The number of hours that college students sleep on a week night is approximated by a normal curve with a mean of 7 hours and a standard deviation of 1.7 hours. Answer the question below using a z table: About what proportion of students sleep less than 5 hours on a week night? (round to whole number) Question 5 options:

Answer 1

The information above is shown in the normal distribution curve shown below

Step 1 : Find the z-score for 5 hours
$z= \frac{5-7}{1.7} =-1.18$ rounded to 2 dp

Step 2: Read the value of z-score on the z-table
As shown in the second picture, the value z at -1.18 is 0.1190

Step 3: The proportion can be written in percentage form which is 11.90% rounded to 12% to nearest whole number