Question

Three friends Thomas, Harry and James went for the marathon and start
their run at 6 A.M. and run through planes and hills on their way and
return at 12 P.M. If their speed on the plane ground is 4 km/h, up the hill
it is 3 km/h and down the hill it is 6 km/h. Find the total distance they
cover during the whole journey.

(A) 15 km
(B) 10 km
(C) 12 km
(D) 18 km

Please give explanation
if you do I will follow and thank all your answers​

Answer 1

Answer:

13

Step-by-step explanation:

Let total distance be x.

Total time =6 AM -12PM = 6hrs

Using unitary method---

Time for 4km/hr=(6/x)*4 hrs

Time for 6 km/hr=(6/x)*6 hrs

Time for 3km/hr=(6/x)*3 hrs

Now,

(6/x)*6+(6/x)*4+(6/x)*3 =6 hrs

=> (6/x)*(6+4+3) = 6

=> (6/x)*13 =6

=> 6/x =6/13

=> 1/x =6/(13*6)

=> x=(13*6)/6 =13km ---Ans.