Emily just finished painting the smallest wall in her room. It took her 1 hour and 40 minutes and she was able to paint at a rate of forty-two square feet per hour. If the wall is thirteen feet long, how tall is it? Round your answer to the nearest foot.
Suppose the wall is x feet tall.
Given the wall is 13 feet long.
Find the area of the wall :
The area is
13
× x = 13x2
42 feet2 is painted by 1 hour.
So, 13x
feet2 will be painted 13x/42 hour i.e
{(13x)×60}/42 minutes i.e 390x/21 minutes.
By given condition ,
390x/21 minutes = 1 hour 40 minutes = 100 minutes.
I.e 390x = 2100
I.e x= 2100/390=210/39 = 5.38
Therefore the wall is 5 .38 feet tall.
First, calculate the total area of the wall.
1 hour and 40 minutes is equivalent to 1 2/3 hours or 5/3 hrs.
if her rate was 42 ft2/hr, then the total area she painted
was
A = 42 * 5/3 = 70 ft2
Now, the formula to find the area of the wall is
A = Lw
Let A = 70 and, L = 13 and w be the height of the wall. So,
A = Lw
70 = 13w
13w/13 = 70/13
w ≈ 5
Hence, the height of the wall is approximately 5 feet tall.
