recategorized
3,386 views
0 votes
0 votes

The speed of a bus during the second hour of the journey is twice that in the first hour. Also, its speed in the third hour is two-third the sum of its speeds in the first two hours. Had the bus travelled for three hours at the speed of the first hour, it would have travelled $120$km less. Find the average speed of the bus for the first three hours.

  1. $100 \text{kmph}$
  2. $80 \text{kmph}$
  3. $70 \text{kmph}$
  4. $60 \text{kmph}$
recategorized

1 Answer

8 votes
8 votes
Let the speed of the bus during the first hour be $t\,kmph$

So, speed during second hour=$2t\,kmph$ and the speed during third hour works out to be $\frac{2}{3} \times (t+2t)=2t\,kmph$

So, total distance travelled by the bus in 3 hours=$t+2t+2t=5t\,km$

Had the bus travelled for 3 hours at the speed of the first hour it would have travelled 120km less

$5t-3t=120\,km$

$t=60$

So, speed during first,second and third hours are $60kmph,120kmph,120kmph$ respectively.

Average speed=$\frac{60+120+120}{3}=100kmph(A)$
Answer:

Related questions

4 votes
4 votes
1 answer
1
Ruturaj Mohanty asked Dec 27, 2018
4,609 views
$N$ is the smallest number that has $5$ factors. How many factors does $N-1$ have?$4$$6$$5$$3$
3 votes
3 votes
4 answers
2
Ruturaj Mohanty asked Dec 27, 2018
876 views
What is the value of $(x \% \text{ of } y) + (y \% \text{ of } x)$?$20 \% \text{ of } x/y$$2 \% \text{ of } x/y$$2 \% \text{ of } xy$$20 \% \text{ of } xy$
4 votes
4 votes
2 answers
3
Ruturaj Mohanty asked Dec 27, 2018
3,176 views
A book contains $100$ pages. A page is chosen at random. What is the chance that the sum of the digits on the page is equal to $8$?$0.08$$0.09$$0.90$$0.10$
7 votes
7 votes
2 answers
4
Ruturaj Mohanty asked Dec 27, 2018
1,298 views
The remainder when $'m+n'$ is divided by $12$ is $8$, and the remainder when $'m-n'$ is divided by $12$ is $6$. If $m>n$, then what is the remainder when $'mn'$ is divide...