Harry was assigned 75 problems for math homework. Harry did 1/5 of them correctly. How many problems did he get correct?

15 problems

Step-by-step explanation:

To find how many problems were correct, find 1/5 of 75:

Divide 75 by 5:

75/5

= 15

So, Harry got 15 problems correct.

5/20 so 25%

step-by-step explanation:

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

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