Advanced Math practice question

Answer: 15

400 → 200 → 100 → 50 is three halvings, and 3 × 5 = 15 hours.

Common wrong answers

If you answered 10

10 hours is two halvings, leaving 100 grams.

If you answered 20

20 hours is four halvings, leaving 25 grams.

If you answered 40

40 comes from 400 ÷ 50 = 8 and then 8 × 5, using the ratio as a count of halvings; 8 = 2³, so three halvings.

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