this is grade 10 math questions
a rectangular window is 5 feet 3 inches in length, and 3 feet 6 inches in width. if the perimeter of the window must have caulking that costs 32cents per inch, how much will the caulking cost??
the answer is $67.20
but i got 846.73 :(
what i did was
5ft=60inch legth= 60 + 3 = 63inches
and for the width
3ft=36inches width= 36 +6 = 42inches
42 x 63 =2646
2646 x 0.32= 846.72
plzz tell me what i did wrong
You found the area, not the perimeter.
P = 2L + 2W
perimeter=2*5feet3inch + 2*3feet6inch
=17feet6inch (1feet=12inch)
total inches = 17*12+6
= 210 inches
210*0.32=67.20
To calculate the length of the window, you correctly converted the feet to inches: 5ft = 60inches. However, you made an error when you added 3 inches to it. Instead, you should add 3 inches and 6 inches separately to get the correct total length.
Length = 60 inches + 3 inches = 63 inches
Similarly, for the width, you correctly converted the feet to inches: 3ft = 36 inches. But then you added 6 inches incorrectly. You need to add it separately to the total width.
Width = 36 inches + 6 inches = 42 inches
Now, you can calculate the perimeter of the window using the correct length and width:
Perimeter = 2 × (Length + Width)
Perimeter = 2 × (63 inches + 42 inches)
Perimeter = 2 × 105 inches
Perimeter = 210 inches
Finally, you can calculate the cost of caulking by multiplying the perimeter by the cost per inch:
Caulking Cost = Perimeter × (Cost per inch)
Caulking Cost = 210 inches × $0.32/inch
Caulking Cost = $67.20
So, the correct caulking cost is $67.20, not $846.72.