LIghtning McQueen starts later but still catches up with King and Chick. And you thought CAT prep was boring.

1. Speed Time Distance

2. Speed Time Distance
Three cars leave A for B in equal time intervals. They reach B
simultaneously and then leave for Point C which is 240 km away from
B. The first car arrives at C an hour after the second car. The third car,
having reached C, immediately turns back and heads towards B. The
first and the third car meet a point that is 80 km away from C. What
is the difference between the speed of the first and the third car?
(a) 60 kmph
(b) 80 kmph
(c) 20 kmph
(d) 40 kmph

3. Speed Time Distance
Three cars leave A for B in equal time intervals. They reach B
simultaneously and then leave for Point C which is 240 km away from
B. The first car arrives at C an hour after the second car. The third car,
having reached C, immediately turns back and heads towards B. The
first and the third car meet a point that is 80 km away from C. What
is the difference between the speed of the first and the third car?
A B C
240km
1
3
80km

4. Speed Time Distance
AB
v1
−
AB
v2
=
AB
v2
−
AB
v3
240
v1
−
240
v2
= 1
v3 = 2v1
Three cars leave A for B in equal time intervals. They reach B
simultaneously and then leave for Point C which is 240 km away from
B. The first car arrives at C an hour after the second car. The third car,
having reached C, immediately turns back and heads towards B. The
first and the third car meet a point that is 80 km away from C. What
is the difference between the speed of the first and the third car?

5. Speed Time Distance
Let v1, v2 and v3 be the speeds of the cars.
Condition I states that the cars leave in equal intervals of time and
arrive at the same time. Or, the difference in the time taken between
cars 1 and 2 should be equal to the time taken between cars 2 and 3.
Three cars leave A for B in equal time intervals. They reach B
simultaneously and then leave for Point C which is 240 km away from
B. The first car arrives at C an hour after the second car. The third car,
having reached C, immediately turns back and heads towards B. The
first and the third car meet a point that is 80 km away from C. What
is the difference between the speed of the first and the third car?

6. Speed Time Distance
We get
AB
v1
−
AB
v2
=
AB
v2
−
AB
v3
As the second car arrived at C an hour earlier than the first, we get a
second equation
240
v1
−
240
v2
= 1
Three cars leave A for B in equal time intervals. They reach B
simultaneously and then leave for Point C which is 240 km away from
B. The first car arrives at C an hour after the second car. The third car,
having reached C, immediately turns back and heads towards B. The
first and the third car meet a point that is 80 km away from C. What
is the difference between the speed of the first and the third car?

7. Speed Time Distance
The third car covered 240 + 80 kms when the first one covered
240 – 80 kms. Therefore,
320
v3
=
160
v1
This gives us v3 = 2v1
Three cars leave A for B in equal time intervals. They reach B
simultaneously and then leave for Point C which is 240 km away from
B. The first car arrives at C an hour after the second car. The third car,
having reached C, immediately turns back and heads towards B. The
first and the third car meet a point that is 80 km away from C. What
is the difference between the speed of the first and the third car?

8. Speed Time Distance
From condition 1, we have
AB
v1
−
AB
v2
=
AB
v2
−
AB
v3
Substituting v3 = 2v1, this gives us
AB
v1
−
AB
v2
=
AB
v2
−
AB
2v1
or
3 x AB
2 x v1
=
2 x AB
v2
or v2 =
4 x v1
3
Solving
240
v1
−
240
v2
= 1, we get
60
v1
= 1 or, v1 = 60 kmph
=> v2 = 80 kmph and v3 = 120 kmph
Answer choice (a)

9. For lots more CAT Level Questions, visit
online.2iim.com