Question

Don't need the answer, just how you would solve this:

Tobin rows 2 miles per hour faster than her opponent. If it takes Tobin 30 minutes to finish a race, and it takes her opponent 45 minutes to finish the same race, how fast does Tobin row?
(A) 4 mph
(B) 5 mph
(C) 6 mph
(D) 30 mph

Answer 1

d = x * 45 opponent
d = ( x + 2) *30 Tobin
x * 45 = ( x + 2) *30
x* 15 = 60
x = 4
x + 2 = 6 mph

Answer 2

(C) 6 mph

Explanation:

Given,

The time taken by Tobin = 30 minutes,

While, the time taken by her opponent = 45 minutes,

So, the ratio of the time taken by tobin and her opponent = 30 : 45

`\because speed\propto (1)/(time)`

Thus, the ratio of speed of tobin and her opponent =
`(1)/(30):(1)/(45)`

= 45 : 30

= 3 : 2

Suppose speed of tobin = 3x and speed of opponent = 2x

Where, x is positive real number,

Difference in speed = 3x - 2x = x

According to the question,

x = 2 miles per hour,

Hence, the speed of Tobin = 3x = 6 miles per hour.

Option (C) is correct