A truck leaves a city at a speed of 40 mph. An hour later, a car leave

Question

A truck leaves a city at a speed of 40 mph. An hour later, a car leaves the same city and travels in the same direction at a speed of 60 mph. What is the distance from the city where the car will reach the truck?

A. 110 miles
B. 120 miles
C. 130 miles
D. 140 miles
E. 150 miles

A. 110 miles
B. 120 miles
C. 130 miles
D. 140 miles
E. 150 miles

CrackverbalGMAT · Answer

We know that   Time = \frac{Distance}{Speed}

Here we consider the relative speed (RS), as the time is when the 2 vehicles are meeting, traveling in the same direction

The RS is the difference of speeds, as they are traveling on a stationary ground in the same direction = 60 - 40 = 20 mph

Distance traveled by the truck in 1 hour = 40 miles

When the car starts moving, it has to cover the difference of 40 miles

Time = \frac{40}{20} = 2 \space hours

Distance traveled by the car in 2 hours = 60 * 2 = 120 miles

Option B

Arun Kumar

yashikaaggarwal · Answer

LCM of speed 40,60 = 120

The cars will meet at 120 miles from the city.

Alternatively,

Time taken by truck = Distance/ Truck speed 
=> T1 = D/40 ---------(1)

Time taken by car = Distance/ Car speed 
=> T2 = D/60 ---------(2)

They both will be travelling same with meet each other.
60T2 = 40T1
3T2 = 2T1
Therefore,
Truck took 3 hours to meet car
3*40 = 120 miles.

Answer is B

Posted from my mobile device

Archit3110 · Answer

from given info we can write
x/40-1 = x/60
solve for x = 120 miles
option B

JohnWidestone · Answer

The equation should look like this:

40 miles/h * x + 40 miles = 60 miles/h * x | for x = hours till the car reaches the truck

40 miles = 20 miles/h * x

Thus the car needs to drive for two hours to catch up with the truck.

As we know in two hours the car covers 120 miles.

So B

Tonkotsu · Answer

A truck leaves a city at a speed of 40 mph. An hour later, a car leaves the same city and travels in the same direction at a speed of 60 mph. What is the distance from the city where the car will reach the truck?

A. 110 miles
B. 120 miles
C. 130 miles
D. 140 miles
E. 150 miles

Still having a bit of a struggle solving this, but I can see 3 approaches:

1)  manually count the distance each car has gone until they meet

A: 0 60 120
B: 40 80 120

2)  Fix an equation for the the distances and set them equal 
A:  d = 60*(x-1) 
B:  d = 40*x 
A & B:  60 = 60x-40x  ==> x = 3

3 * 60 - (60 _{1st\_hr}) = 120.

3)  Find the time necessary to close the gap and multiply the car's speed by it

gap=(relative speed)*time 
 catchup=time * carspeed

gap = 40 miles 
 relative\_speed = 60 - 40 
 40 = 20mph * time

120 = 2 * 60

bumpbot · Answer

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A truck leaves a city at a speed of 40 mph. An hour later, a car leave

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A truck leaves a city at a speed of 40 mph. An hour later, a car leave

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