Z-score help

hi, i have problems for homework pertaining to z-scores. each problem
has four parts:

ex:the problem is... as of this writing the most recent oscar-winning
best actress was Helen Mirren, who was 61 at the timeof the award. The
Oscar-winning Best Actress have a mean age of 35.8 years and a
standard deviation of 11.3 years

a) what is the difference between Helen Mirren's age and the mean age
b)How many standard deviations is that(the difference found in part a)?
c)Convert Helen Murren's age to a z-score
d)If we consider "usual" ages to be those that convert to z scores
between -2 and 2, is Helen Mirren's age usual or unusual?

i get what part a and d are asking but b and c i don't get at all

erinyvonne said:

hi, i have problems for homework pertaining to z-scores. each problem
has four parts:

ex:the problem is... as of this writing the most recent oscar-winning
best actress was Helen Mirren, who was 61 at the timeof the award. The
Oscar-winning Best Actress have a mean age of 35.8 years and a
standard deviation of 11.3 years

Click to expand...

b)How many standard deviations is that(the difference found in part a)?

Click to expand...

The number of standard deviations is the z-score. \(\displaystyle z=\frac{x-\mu}{\sigma}\).

That's what a z-score measures. Suppose her age were 47.1. Then, she would be 1 S.D above the mean of 35.8.

\(\displaystyle z=\frac{47.1-35.8}{11.3}=1\)

See now?.

c)Convert Helen Murren's age to a z-score

Click to expand...

found above. Match the z-score to the probability in the z-table to find the probability of someone her age winning the Oscar.

Theoretically, that is what it would measure. Though, in reality, it would be more subjective than that.