Mr. R.’s World of Math

clogged tub exemplar

Lesson: Clogged Tub
Skills: Number sense, fractions
Grade Level: 5-6


Each day I give my pet llama a bath in the bathtub- he’s a clean llama. It takes 8 gallons to wash the llama. On the first day the 8 gallons go right down the drain, but each day after that, because there’s so much llama fur in the tub, only half as much water goes down the drain.

For example:

On the second day, only 4 gallons go down the drain, while 4 gallons are stuck in the tub.

On the third day, only 2 gallons go down the drain, while 6 more gallons are stuck in the tub.

Question:
If this pattern continues, how many days will it be before there is 56 and 1/32 gallons of water in the bathtub?

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