Vasantha Sankar

· started a discussion

· 1 Months ago

The numerical values given in question and solution does not match and answer is wrong

The ratio between the speeds of a truck, car and train is 3 : 8: 12. The car moved uniformly and covered a distance of 1040 km in 13 hours. What is the average speed of the truck and the train together?
A) 74 km/h 
B) 60 km/h
C) 48 km/h
D) Cannot be determined

Ans (c) 

The ratio between the speeds of the truck, car and train is 3: 8: 12.

Given that the car covers 1040 km in 13 hours, the speed of the car 80 km/h

Also, if we assume that the speeds of the truck, car and train are 3x, 8x and 12x 

respectively, then

Speed of car = \(\cfrac{1040}{13}\) = 80 kmph

Ratio of speed of truck, car and train = 3 : 8 : 12

Now, 8x = 80 => x = 10 

Hence, truck = 30 kmph 

Train = 120 kmph

Therefore, Average speed of truck and train together = \(=\cfrac{2\times x\times y}{x+y}\)

=\(=\cfrac{2\times 30\times 120}{30+120}=48km/h\)

Knowledge Expert

· commented

· 1 Months ago

Dear student We have updated the solution, please solve it again. Keep learning Team TR