Homework Help: 8th grade math

Posted by liz on Sunday, December 4, 2011 at 12:11pm.

if a person is 6 feet tall and casts a 9 foot shadow, how tall would the shadow of a 100 foot tall tree be?

8th grade math - Anonymous, Sunday, December 4, 2011 at 12:15pm
6 / 9 = 100 / x Multiply both sides with x

6 x / 9 = 100 Multiply both sides with 9

6 x = 9 * 100

6 x = 900 Divide both sides with 6ž

x = 900 / 6

x = 150 ft

OR

9 / 6 = 1.5

x / 100 = 1.5 Multiply both sides with 100

x = 1.5 * 100

x = 150 ft
8th grade math - MathMate, Sunday, December 4, 2011 at 1:52pm
or using proportions and cross multiply:
6:9
100:?
? = 100*9/6=150
8th grade math - amy, Monday, December 10, 2012 at 3:38pm
A tree and a building stand side by side. The 5-foot tall tree casts a shadow of 12 feet. If the building is 80 feet tall, how long is its shadow?

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