width --- x
length --- (6/5)x
(6/5)x^2 = 480
x^2 = 400
x = √400 = 20
picture is 20 inches by 24 inches
Sally painted a picture that has an area of 480 square inches. The length of the painting is 1 1/5 its width. Which of the following could be the
dimensions of Sally’s painting?
A. 20 inches by 24 inches
B. 12 inches by 40 inches
C. 16 inches by 30 inches
D. 15 inches by 32 inches
3 answers
1.2 * 20 = 24
1.2 * 12 = 14.4
1.2 * 16 = ?
1.2 * 15 = ?
1.2 * 12 = 14.4
1.2 * 16 = ?
1.2 * 15 = ?
A.
Explination:
Let x = width
Let (6/5)x = length (NOTE: 6/5 is the same as 1 1/5)
Area = width * length
480 square inches = x * (6/5)x
480 = (6/5)x^2 (NOTE: now use order of operations)
400 = x^2 (NOTE: take the square root of both sides, to cancel out the exponent)
20 = x
If x = width, then width = 20.
A is the only choice with 20 as the width.
Explination:
Let x = width
Let (6/5)x = length (NOTE: 6/5 is the same as 1 1/5)
Area = width * length
480 square inches = x * (6/5)x
480 = (6/5)x^2 (NOTE: now use order of operations)
400 = x^2 (NOTE: take the square root of both sides, to cancel out the exponent)
20 = x
If x = width, then width = 20.
A is the only choice with 20 as the width.
1 answer