Question

(ii) If the speed of a car is increased by 12 km/h, it takes 40 minutes less to cover a
distance of 240 km. Find the original speed of the car.​

Answer 1

Given:

If the speed of a car is increased by 12 km/h, it takes 40 minutes less to cover a distance of 240 km.

To find:

The original speed of the car

Solution:

The distance covered by the car = 240 km

Let's consider,

"S km/hr" → represents the original speed of the car

"(S + 12) km/hr" → represents the increased new speed of the car

We know,

$\boxed{\bold{Time = \frac{Distance }{Speed} }}$

According to the question and the formula above, we can form an equation as:

$\frac{240}{S} - \frac{240}{S+ 12} = \frac{40}{60}$

$\implies 240 [\frac{1}{S} - \frac{1 }{S + 12} ] = \frac{2}{3}$

$\implies \frac{1}{S} - \frac{1 }{S + 12} = \frac{1}{360}$

$\implies \frac{S+ 12 - S}{S(S+12)} = \frac{1}{360}$

$\implies \frac{ 12 }{S(S+12)} = \frac{1}{360}$

$\implies S^2 + 12S = 4320$

$\implies S^2 + 12S - 4320 = 0$

$\implies S^2 + 72S - 60S - 4320 = 0$

$\implies S(S + 72) - 60(S + 72) = 0$

$\implies (S + 72) (S - 60) = 0$

$\implies S = -72 \:or\: 60$

since speed cannot be negative, so taking the positive value of the speed

$\implies \bold{S = 60 \: km/hr }$

Thus, the original speed of the car is → 60 km/hr.

--------------------------------------------------------------------------------------------

Also View:

If the speed of a car is increased by 10km/hr, it takes 18min less to cover a distance of 36km then find the speed of the car

brainly.in/question/1052274

The car increases its speed by 25%. After that, it again increases by 20%. By what percentage is the car's final speed greater than the original?

brainly.in/question/5331186

if the speed of the car is increased by 15 kmph, It takes 2 hours less to cover a distance of 600km. Find usual time for the journey

brainly.in/question/8985999

Answer 2

Step-by-step explanation:

answer of the following question