SSC CGL 24 Aug 2021 Shift 2 Paper

Question : 71 of 100

Marks: +1, -0

Places

A

and

B

are

45 {km}

apart from each other.

A

car starts from Place

A

and another car starts from Place

B

at the same time. If they move in the same direction, they meet in

4.5 {h}

and if they move towards each other, they meet in

27 {min}

. What is the speed (in

{km} \/ {h}

) of the car which moves faster?

Solution:

Given, distance

=45 {km}

.
Let the speed of fast car

=x

and the speed of slow car

=y

When move in same direction speed

∴ \;\; (x-y)=\;{\;\text " distance "\;}/{\;\text " Time "\;}

∵ \;\; x-y=

Speed
Time

=4.5 {h}

and Distance

=45 {km}

⇒ \;\; x-y=\;{45}/{4.5}=10

⇒ \;\; x-y=10

. . . (i)
When move in opposite direction speed will add

⇒ \;\; x+y=\;{45}/{{27}/{60}}

\;\; [ ∵ \;\text " Time "\;=27 {min} \;\text " or "\;=\;{27}/{60} {h}]

\;\; x+y=100 {km} \/ {h}

. . . (ii)
From Eq. (i)

+

Eq. (ii),

x-y+x+y \;\; =10+100

⇒ \;\; 2 x \;\; =110

⇒ \;\; x \;\; =55 {km} \/ {h}

\;\text " Speed of faster car "\; x=55 {km} \/ {h} .

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