Question

A worker takes a random sample of 320 bolts and finds that 30 of them are either too long or too short, thus making them unusable. Estimate the number of unusable bolts in a production of 14,000 bolts.
1,313 bolts
1,400 bolts
1,300 bolts
1,320 bolts

Answer 1

@JoannaBlackwelder

Answer 2

Can you find the probability of unusability using the 320 bolts with 30 of them unusable?

Answer 3

320 * 30?

Answer 4

No, it's the same formula as last time.

Answer 5

(number of unusable/total number)*100

Answer 6

@JoannaBlackwelder Well 30 were unusuable it said and the total number was 14,000, so it's 30 / 14,00 * 100?

Answer 7

We don't know how many are unusable when we have 14,000 total. That is what we are looking for. But we have both numbers when the total is 320 and the number unusable is 30.

Answer 8

Ok, so then it would be 30/320 right?

Answer 9

Right, *100 :-)

Answer 10

And then that is 0.09 and I would times that by 100 ?

Answer 11

Yep

Answer 12

And that's 9.37

Answer 13

Yep, I get 9.375 to be precise. :-)

Answer 14

Lol, right, so then...is there another step? To get it to be one of the answers?

Answer 15

Then we can use that value in the same formula, but when the total is 14,000

Answer 16

So, 9.375=(number unusable/14,000)*100

Answer 17

See how I wrote that formula?

Answer 18

Lol, not really...I got 0.066

Answer 19

It is probability = (number unusable/total number)*100

Answer 20

How did you get .066?

Answer 21

I did 9.375 / 14000 * 100

Answer 22

No, the 9.375 is the probability, not the number of unusable.

Answer 23

Any ideas how to solve?