The mean hourly income of midwives in NJ is $55 with standard deviation of $15. Given that the distribution is normal, what percentage of NJ midwives earn more than $60 per hour?

A.10%
B.25%
C.70%
D.none of the above

Respuesta :

Answer: D. none of the above

Step-by-step explanation:

Let x = a random variable that denotes the hourly income of midwives.

As per given , we have

[tex]\mu=\$55[/tex]

[tex]\sigma=\$15[/tex]

Also, the distribution is normal.

Then, the probability that NJ midwives earn more than $60 per hour will be :_

[tex]P(x>60)=1-P(x<60)=1-P(\dfrac{x-\mu}{\sigma}<\dfrac{60-55}{15})\\\\=1-P(z<0.33)\ \ [\because\ z=\dfrac{x-\mu}{\sigma}]\\\\=1-0.6293\ \ [\text{By z-table}]\\\\ =0.3707=37.07\% [/tex]

Hence, the percentage of NJ midwives earn more than $60 per hour is  approximately 37.07%.

Since , 37.07% is not given in any option.

So the correct answer to this question is "D.none of the above"