100 aaa batteries were tested on a particular mp3 player. suppose the battery has a mean lifetime of 31.7 hours, with a standard deviation of 2.9 hours. how long do we expect the majority of batteries to last? a. between 2.9 and 31.7 hours
b. between 28.8 and 31.7 hours
c. between 31.7 and 34.6 hours
d. between 28.8 and 34.6 hours

31.7 -2.9 = 28.8

31.7 + 2.9 = 34.6

 between 28.8 & 34.6 hours

D is the correct answer

answer

explanation

the area of a circle is calculated using the formula

or

we can use any of the above formulae to calculate the required. preferably, let us use the latter since the diameter is

we substitute the diameter into the formula to get:

this is the exact value for the area of the circle.

the correct answer is a

7

step-by-step explanation: