CTET 2 Math and Science Jan 2021 Paper

Question : 86 of 150

Marks: +1, -0

Neena was cycling to the market to buy some grocery items. The market is

4 {\km}

away from her home. She travels at a speed of

12 {\km} \/ {\h}

for first

10 {\min}

. On her way she meets her friend Nikhat and stops to chat with for

15 {\min}

. She resumes her journey at a speed of

8 {\km} \/ {\h}

. What is her average speed for the journey?

Solution:

According to the question,

Given,

T_{1}=10 {\min}={10}/{60}={1}/{6} {\h}

S_{1}=12 {\km} \/ {\h}

T_{2}=15 {\min}={15}/{60}={1}/{4} {\h}

S_{2}=8 {\km} \/ {\h}

First travelled distance,

D_{1}=S_{1} ×T_{1}

=1/6×12=2\km

Second travelled distance

D_2=D-D_1

=4\km-2\km=2\km

Time required to travel second distance

T_{3}={D_{2}}/{S_{2}}={2}/{8}={1}/{4} {\h}

Total time

T=T_{1}+T_{2}+T_{3}

=1/6+1/4+1/4

=1/6+2/4 =2/3\h

Average speed

={\text "Total distance " }/{\text " Total Time "}

={4×3}/2

= 6 km/h

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