Question

A bag contains 15 new batteries and 10 used batteries. If Heather randomly selects 2 batteries from the bag without replacement, what is the probability she will select a used battery and then a new battery? Show work

Answer 1

well, 60% of 25 is 15, and 40% of 25 would be 10. So, it should be a 60-40 percent chance. so, the probability of an used one is lower than a new one by 20%

I may sound confusing so to sum it all up : It is lower than the new batteries because, the old ones would be a 40% chance while the new ones would be 60%.

Answer 2

There are 15 N (15 new batteries), and there are 10 U (10 used batteries)

The ratio is 3N : 2U

the chance of taking 1 N is 3/5 (60%)

the chance of taking 1 U is 2/5 (40%)

To grab both a new battery and an old battery multiply 3/5 * 2 / 5 = 6 / 25 (24%). To find the percentage from 6 / 25 multiply by 4 so the 25 becomes 100 and the 6 becomes the percentage, in this case 24 %.

Answer: 24 %