Question

Sobha drove her car at a certain speed for the first 4 hours and increased its speed by 10km./hr. for the next two hours. If the total distance travelled by her was 500km. find the speeds at which Sobha drove her car at different times

Answer 1

Answer:

Speed of the car in first 4 hours = 80 km/hour

Speed of the car in next 2 hours = 90 km/hour

Step-by-step explanation:

Formula used:

$speed=\frac{Distance}{Time}$

Let x be the distance covered by the car in first 4 hours.

Then, the distance covered by the car in next 2 hours is (500-x)

case(i):

$speed=\frac{Distance}{Time}$

$s=\frac{x}{4}$

$\implies\:x=4s$..............(1)

case(ii):

$speed=\frac{Distance}{Time}$

$s+10=\frac{500-x}{2}$

$\implies\:500-x=2s+20$..........(2)

Adding (1) and (2)

$x+(500-x)=4s+2s+20$

$500=6s+20$

$500-20=6s$

$480=6s$

$s=\frac{480}{6}$

$s=80$ km/hour

Speed of the car in first 4 hours = 80 km/hour

Speed of the car in next 2 hours = 90 km/hour

Answer 2

Answer:

Speed in first 4 hours  = 80 km/Hr

Speed in next 2 hrs = 90 km/hr

Step-by-step explanation:

Sobha drove her car at a certain speed for the first 4 hours and increased its speed by 10km./hr. for the next two hours. If the total distance travelled by her was 500km.

Let say speed in first 4 hrs = S km/Hr

Then Speed in next 2 hrs = S + 10 km/Hr

Distance = Speed * Time

Distnace in 1st 4 hrs = 4S km

Distance in next 2 hrs = 2(S +10) = 2S + 20 km

4S + 2S + 20 = 500

=> 6S = 480

=> S = 80

S + 10 = 90

Speed in first 4 hours  = 80 km/Hr

Speed in next 2 hrs = 90 km/hr