# Distance and Time Quiz Set 015

### Question 1

A boy walks along the three edges of an equilateral triangle at average speeds of 5 km/h, 9 km/h and 9 km/h. What is the average speed along the whole journey?

A

\$7{2/19}\$ kmph.

B

\$8{5/9}\$ kmph.

C

\$5{11/21}\$ kmph.

D

\$9{1/7}\$ kmph.

Soln.
Ans: a

Let the edge of the triangle be L. Total distance travelled = 3L. Time taken = \$L/5 + L/9 + L/9\$. So overall average speed = \${3L}/{L/5 + L/9 + L/9}\$ which simplifies to \${135/19}\$, which is same as: \$7{2/19}\$ km/h.

### Question 2

Speeds of A and B are in the ratio 12 : 17. What is the speed of A if B can cover a distance of 34 Km in 1 hour?

A

24 kmph.

B

25 kmph.

C

23 kmph.

D

26 kmph.

Soln.
Ans: a

The speed of B is 34/1 = 34 km/h. So, the speed of A = \${12 × 34}/17\$ = 24 km/h.

### Question 3

A car is moving at a speed of 72 kmph. What is the speed in m/s?

A

20 m/s.

B

21 m/s.

C

19 m/s.

D

22 m/s.

Soln.
Ans: a

We know 1kmph = \$5/18\$ m/s. So 72kmph = \$5/18 × 72\$ = 20 m/s.

### Question 4

An aircraft was on a 1360 km journey. Its engine developed a snag so it had to slow down. It's average speed reduced by 5km/h, as a result of which it reached its destination late by 1 hour. What was the actual duration of the journey?

A

16 hrs.

B

17 hrs.

C

15 hrs.

D

18 hrs.

Soln.
Ans: a

Let x be the actual duration of the journey. Then, \$1360/x - 1360/{x + 1} = 5\$. Which gives 1360 × \$1/{x (x + 1)} = 5\$. Solving for x, or by trying the options one by one, we get x = 16 hours.

### Question 5

Speeds of A and B are in the ratio 7 : 9. What is the ratio of the times that they will take to cover a distance of 100 km?

A

9 : 7.

B

7 : 9.

C

9 : 100.

D

100 : 7.

Soln.
Ans: a

Let the speeds be 7x and 9x. The times they take to cover 100 km are \$100/{7x}\$ and \$100/{9x}\$. The ratio would be 9 : 7. 