IQs as measured by the Wechsler Adult Intelligence Scale are approximately Normal with mean 100 and standard deviation 15. About 84% of people will have IQs below 115 because 115 is standard deviation(s) above the mean.

1 standard deviation

Step-by-step explanation:

Given that :

IQs as measured by the Wechsler Adult Intelligence Scale are approximately Normal with:

Mean = 100

Standard deviation = 15

About 84% of people will have IQs below 115 because:

84% = 0.84

From z - table, 0.84 corresponds to a z- score of about 0.995

0.995 = 1. 00

The z-score gives the number of standard deviations by which a raw score is above or below the average or mean value.

Raw score = 115

Mean = 100

Standard deviation (sd) = 15

Mean + number of sd's

100 + 1(sd)

100 + 1(15) = 100 + 15 = 115

he spend 5.1 minutes chatting with his friends

step-by-step explanation:

2/5+1/2=9/10

6/1-9/10=5 1/10

step-by-step explanation:

b and c