Question

A car is designed to last an average of 12 years with a standard deviation of 0.8 years.

Answer 1

Yes what is your question?

Answer 2

What is the probability that a car will last less than 10 years?

Answer 3

ok you need to calculate a z and then look up on a z table.

Answer 4

what

Answer 5

how do i do it

Answer 6

The z formula is you take the (value-mean)/standard deviation.

Answer 7

would the mean be 12?

Answer 8

so 12/.8

Answer 9

no (10-12)/.8

Answer 10

Yes the mean would be 12

Answer 11

But 10 is what you are interested in.

Answer 12

so -2.5?

Answer 13

@Evoker

Answer 14

what next

Answer 15

Ok, now look up on a z table, your book probably has one in it which tells you the probability of a value being less than or equal to a z of -2.5

Answer 16

okay but then which column do you look up

Answer 17

none of the values are any of the answer choices

Answer 18

Hmm let me find a table

Answer 19

I see .0062 or .62% chance

Answer 20

thats none of the options

Answer 21

Hmm strange that should be correct.

Answer 22

What options do you have out of curiosity

Answer 23

0.621%
6.21%
93.79%
99.379%

Answer 24

@Evoker

Answer 25

so a maybe?

Answer 26

That is the first answer

Answer 27

yeah just not to the same level of precision.

Answer 28

okay

Answer 29

okay i thought so the 1 kinda threw me off

Answer 30

It depends on what table you use, your text must have a z table with more precise results.