Question

A road crew can pave 2/5 km in 1 1/2 hours.how many km of road can they pave in 10 hours?

Answer 1

8/3 km

Explanation:

we can represent the given information on a table:

Kilometers time (hours)

2/5 ⇔ 1 1/2

and since we want to know how many kilometers (x) will be paved on 10 hours:

Kilometers time (hours)

2/5 ⇔ 1 1/2

x ⇔ 10

The relationship these 3 numbers have can be described by using the rule of three, which is to multiply the cross quantities on the table (2/5 by 10) and then divide by the remaining amount (1 1/2):

x =
`(2)/(5)*10` ÷
`1(1)/(2)`

x =
`(20)/(5)` ÷
`1(1)/(2)`

we use
`1(1)/(2)=(3)/(2)`

x =
`(20)/(5)` ÷
`(3)/(2)`

and we make the division:

x =
`(20)/(5)` ÷
`(3)/(2)` =
`(20*2)/(5*3)=(40)/(15)`

we simplify the fraction by dividing the numerator and denominator both by 5, and we get the result:

x =
`(8)/(3)`

thus, in 10 hours the crew will pave 8/3 km. Which is about 2.66 km.