Question

I need help with finding the percentage. I'm confused on this problem. Will someone walk me through the steps?

A local zoo has on average 250 visitors per day during its peak season with a standard deviation of 80. Assume that the variable is normally distributed.

1. Find the probability that the zoo will have less than 100 visitors.

Answer 1

are you allowed to use a calculator

Answer 2

Yes

Answer 3

do you have a TI calculator?

Answer 4

Nope.

Answer 5

ok then we'll have to use wolfram alpha

Answer 6

Alright. So what would I do?

Answer 7

you would type this in

normalcdf(0,100,250,80)

the first two numbers 0 and 100 represent the interval under the curve we want to find, basically we want the area under the curve from 0 to 100

the next two numbers are the mean (250) and the standard deviation (80)

Answer 8

if you type that in, you'll get this link

http://www.wolframalpha.com/input/?i=normalcdf%280%2C100%2C250%2C80%29

Answer 9

now look at the row that says 0 < z < 100

next to that is the number 0.02951

Answer 10

so the area under the curve from 0 to 100 is 0.02951

this means that the probability is roughly 0.02951 (which is a 2.951% chance roughly)

Answer 11

Thank you very much.

Answer 12

yw