Question

QUESTION 8

The amount of time an investment banker devotes to his/her job per week is normally distributed with a mean of 70 hours and a standard deviation of 5 hours.

Find the probability that the mean amount of work per week for 9 randomly selected investment bankers is more than 72 hours. (Find the nearest answer.)

   a.  
0.06681

   b.  
0.11507

   c.  
0.2275

   d.  
0.15866

   e.  
0.22663

1 points

Answer 1

X = The amount of time an investment banker devotes to his/her job per week

X N(, )  

= 70

= 5

n = 9

since X N(, )  then

N(, /n^1/2 )

Z = ( -  )//n^1/2  

P( > 72) = P{( -  )//n^1/2 > [(72 - 70)/5/9^1/2]}

= P(z > 6/5)

= P(z > 1.2 )

= 1 - P(z < 1.2)

= 1 - 0.88493  

= 0.11507

Thus (b) is correct option.