Question

A drawbridge rises at a constant rate. It takes 1 1/2 minutes for the drawbridge to rise 6/20 of its total height. How much tike, in minutes, does it take for the drawbridge to reach its total height?

a) 1/5

b)9/20

c)20/9

d)5

Answer 1

the awnser would be c

Answer 2

Option d. 5

Explanation:

A drawbridge takes
`1(1)/(2)` minutes to rise
`(6)/(20)` of its total height.

Let the total height of the drawbridge is h units

∵ Drawbridge rises
`(6h)/(20)` units in the time =
`(3)/(2)` minutes

∴ Drawbridge rises 1 unit in the time =
`((3)/(2) )/((6h)/(20))` minutes

∴ Drawbridge rises h units in the time =
`((3)/(2) )/((6h)/(20))* h`

=
`(3h)/(2)* (20)/(6h)`

=
`(60)/(12)`

= 5 minutes

Option d. 5 minutes is the answer.