Q:

The mean midday temperature recorded in June in a city in South California is 36ºC, and the standard deviation is 3ºC.Assuming the data is normally distributed, the number of days in June when the midday temperature was between 39ºC and 42ºC is .

Accepted Solution

A:
mean = 36sd = 3P( 39 < x < 42) = P(( 39 - 36) / 3 < Z < ( 42 - 36) / 3)P(3/3 <z<6/3)
 P( 1 < Z < 2) = P( x < 2) - P( x < 1) = 0.9772 - 0.8413 = 0.1359
(need to use the normal probability table to get the decimal numbers) 
June has 30 days

 0.1359*30 = 4.0777 days, round to 4 days