Question

Amit goes to his office by car at the speed of 80 km/hr and reaches 15 minutes earlier. if he goes at the speed 60 km/hr, he reaches 15 minutes late. what will be the speed (in km/hr) of the car to reach on time?

Answer 1

the speed will be 75 km/hr to reach their on time.

Answer 2

Answer:

$speed$ = $68\frac{4}{7} \frac{km}{hr}$

Step-by-step explanation:

According to this question

We have been given that

He goes with the speed of $80\frac{km}{h}$ and reaches 15 minutes earlier and if he goes at the speed 60 km/hr, he reaches 15 minutes late.

Now, we know that

$speed$ = $\frac{distance}{time}$

Distance is same

Let, time = x

So, 80 = $\frac{distance}{x - 15}$

60 = $\frac{distance}{x + 15}$

Divide both equation

$\frac{80}{60}$ = $\frac{\frac{distance}{x - 15}}{\frac{distance}{x + 15}}$

$\frac{8}{60}$ = $\frac{x - 15}{x + 15}$

8x + 120 = 6x - 90

2x = 210

x = 105 minutes

$x$ = $\frac{105}{60} hours$

Now, we finding the distance

 80 = $\frac{distance}{/frac{105 - 15}{60}}$

$distance$ = $80\times \frac{90}{60}$

Distance = 120 km

So, $speed$ = $\frac{120}{\frac{105}{60}}$

$speed$ = $\frac{120\times 60}{105}$

$speed$ = $\frac{480}{7}$

$speed$ = $68\frac{4}{7} \frac{km}{hr}$