Question

the number of students failed in chemistry exam is changed from 20 to 12 . what is the decrease percent?​

Answer 1

p=40%

Explanation:

20-12=8

8=p/100 *20=20p/100=p/5

p=8*5=40

p=40

Answer 2

40%

Explanation:

percentage decrease

=
`(original - new \: value)/(original) * 100\%`

Percentage decrease

`= (20 - 12)/(20) * 100\% \\ = (8)/(20) * 100\% \\ = 40\%`

You could also first calculate the percentage change then get rid of the negative sign to find percentage decrease.

percentage change

= (new -original)/original ×100%

= (12 -20)/20 ×100%

= -40%

Thus, percentage decrease= 40%.