Question

THE RATIO OF SPEEDS OF TWO CARS PER HOUR IS 7:9. IF THE FASTER CAR COVERS THE DISTANCE OF 135KM IN 5 HOURS, FIND THE TIME TAKEN BY THE OTHER CAR TO COVER SAME DISTANCE

ANSWER CORRECTLY WITH SOLUTION
NO. SPAM​

Answer 1

as the 1st car covers 135km in 5 hours therefore, it's speed will be 135/5=27kmph

therefore, by substituting the value in the ratio,

the other car's speed will be 21kmph

therefore, time taken by it to cover 135km will be 135/21hr

Answer 2

Given is the ratio of speeds of two cars, Find the time taken by the slower car to cover the same distance as that by the faster car.

Explanation:

• Let the speed of the faster car be denoted by 'S1'.
• Let the speed of the slower car be denoted by 'S2'.
• Now given is the ratio of both the cars to be $7:9$.
• Hence we from the ratio we get that, $\frac{s_1}{s_2}=\frac{9}{7} \ \ \ \ \ \ ->s_2=\frac{7}{9} s_1$  ---(a)
• Now the speed of a car covering the distance 'd' kilometers in 't' hours of time is given by, $s=\frac{d}{t}\ km/h$
• Now for the faster car we have, $d=135\ km,\ t=5\ hrs$  
• Hence the speed of the faster is, $s_1=\frac{135}{5}=27 \ km/h$  
• Now putting this value of speed in (a) we get the speed of the slower car,    $s_2=\frac{7}{9}(27) =21\ km/h$  
• Now the time taken by the slower car to cover the same distance is, $T=\frac{d}{s_2}=\frac{135}{21}\ \ \ \ \ ->T\approx 6.43\ hrs$
• Hence the slower car covers the distance of $135\ km$ in nearly $6.43\ hrs.$