Question

An electrician bought 120 feet of electrical wire and used 105 feet of it. What percent of the wire went unused? 15% 12. 5% 8. 75% 7%.

Answer 1

The percent of the wire that went unused was 15%.

Explanation:

You can set up these equations:

Turn 15% into 0.15

12.5% into 0.125

8.75% into 0.0875

7% into 0.70

Now, the number of wire unused is 15. Since 120 - 105 = 15. So, we can set up these equations to see which percentage it was that got unused:

0.15 x 120 = 18

0.125 x 120 = 15

0.0875 x 120 = 10.5

0.70 x 120 = 84

So, the answer is 15%.

Answer 2

12.5%

Explanation:

105 is what percent of 120?

you can use this proportion:

if/of = %/100

in this problem:

is = 105

of = 120

'what percent' = p/100

105/120 = p/100

cross-multiply to get:

120p = 10500

p = 10500/120

p = 87.5

So the electrician used 87.5%, out of 100%, meaning 12.5% went unused