Question

A waiter believes the distribution of his tips has a model that is slightly skewed to the right​, with a mean of ​$12.50 and a standard deviation of ​$8.40. He usually waits on about 70 parties over a weekend of work. ​a) Estimate the probability that he will earn at least ​$900. ​b) How much does he earn on the best 10​% of such​ weekends? How would this be done on a ti-84 plus CE calculator?

Answer 1

For TI-84 Calculator: (a)

Step 1: Press 2^nd VARS [DISTR].

Step 2: Scroll down to

Step 3: 2:normalcdf(

Press ENTER.

Step 4:

Enter 900,9999,875,70.279)
and press ENTER
to get the answer .0712.

The syntax is normalcdf(smaller, larger, µ, σ).

(b)

Step 1: Press 2^nd VARS [DISTR].

Step 2: Scroll down to 2 times

Step 3: 3: NormInv

Press ENTER.

Step 4:

Enter 0.90,875,70.279)
and press ENTER
to get the answer 965.066