Question

6. A caterpillar crawls at a speed of 21cm per hour towards a vegetable patch.
After eating its fill it returns, over the same distance, at only 7cm per hour. Not
including the eating time, what is the caterpillar's average speed over the entire
journey?
5.2cm/hour
7.0cm/hour
10.5cm/hour
14cm/hour

Answer 1

${\large{\bf{\red{\underline{Given :}}}}}$

A caterpillar crawls at a speed of 21cm/h towards a vegetable patch.After eating it's food it returns,over the same distance at only 7cm/h .

_____________________

${\large{\bf{\blue{\underline{To Find :}}}}}$

Find the average speed of catterpillar .

_____________________

${\large{\bf{\orange{\underline{Solution :}}}}}$

Formula to use :

${\blue{\bigstar{\pink{\boxed{\mathfrak{Average \: speed = \frac{total \: distance \: covered}{total \: time \: taken} }}}}}}$

First case :

Distance covered = 21cm

Time taken = 1 hr

Second case :

Distance covered = 7cm

Time taken = 1hr

Average speed :

${\green{\mapsto{\bf{ \frac{total \: distance \: covered}{total \: time \: taken} }}}}$

${\green{\mapsto{\bf{ \frac{21 + 7}{2} }}}}$

${\green{\mapsto{\bf{ {\cancel\frac{28}{2} }}}}}$

${\blue{\mapsto{\red{\boxed{\bf{14cm/h}}}}}}$

So,

The average speed of catterpillar is 14cm/h.

________________________