Question

A car moves a distance of 200 m. It covers the
first half of the distance at speed 40 km/h and
the second half of distance at speed v. The
average speed is 48 km/h. Find the value of v
(a) 56 km/h (b) 60 km/h
(c) 50 km/h (d) 48 km/h

Answer 1

HEY MATE YOUR ANSWER IS HERE...

TOTAL DISTANCE = 200 m

1st HALF DISTANCE SPEED = 40 Km / h

2nd HALF DISTANCE SPEED = X Km / h

AVERAGE SPEED = 48 Km / h

NOW ,

AVERAGE SPEED =

TOTAL DISTANCE / TOTAL TIME

NOW ,TOTAL TIME =

$speed \: = \frac{distance \: }{time} \\ \\ time \: = \frac{distance}{speed}$

NOW TOTAL TIME =

$\frac{100}{40} + \frac{100}{v}$

HENCE ,AVERAGE SPEED =

$48 \: = \frac{200}{ \frac{100}{40} + \frac{100}{v} }$

$\frac{1}{24} = \frac{1}{40} + \frac{1}{v} \\ \\ v = \frac{120}{5 - 3} \\ \\ v = \frac{120}{2} \\ \\ v = 60 \: </strong><strong>km\</strong><strong>:</strong><strong> </strong><strong>per </strong><strong>\</strong><strong>:</strong><strong> </strong><strong>hrs</strong><strong>$

HENCE OPTION (B) IS CORRECT

THANKS FOR YOUR QUESTION HOPE THIS HELPS

★ KEEP SMILING ☺️✌️ ★