statistics
posted by millli on .
Bill spends an average of 5 minutes each day waiting in lines. If Bill is typical of the 290 million people in the United States, which of the following expresses the approximate combined amount of time these people spend annually waiting in line?
A. 1.45 × 109 minutes a year
B. 14.5 × 108 minutes a year
C. 1.825 × 103 minutes a year
D. 0.52925 × 1010 minutes a year
E. 5.2925 × 1011 minutes a year
Skip this question for now.

millli, for your information, scientific notation can be written as
1.45x10^9, or 1.45x10E9.
So the above choices are really:
A. 1.45 × 10^9 minutes a year
B. 14.5 × 10^8 minutes a year
C. 1.825 × 10^3 minutes a year
D. 0.52925 × 10^10 minutes a year
E. 5.2925 × 10^11 minutes a year
The total number of minutes will therefore be
5 min/person/day * 365 days/year *290x10^6 people
I'll let you do the calculator exercise. 
idkk

The time it takes a student to walk from the dorm to the chemistry lab follows approximately a Normal distribution with a mean of 20 minutes and a standard deviation of 3 minutes.
What are the walking times of the middle 90% of the students to walk from the dorms to the chemistry lab?