Question

CH08: NCERT EX 3. Abdul, while driving to school, computes the average speed for his trip to be 20 km h-!. On his return trip along the same route, there is less traffic and the average speed is 30 km h-!. What is the average speed for Abdul's trip? 20 kph HOME SCHOOL 30 kph​

Answer 1

${\large\textbf{\underline\pink {★ Appropriate \: Question}}}$

Abdul, while driving to school, computes the average speed for his trip to be 20 km h^-1 On his return trip along the same route, there is less traffic and the average speed is 30 km h^-1. What is the average speed for Abdul's trip?

$\large\sf \red { \underline{★ GIVEN}}$

• The averege speed for abdul's trip to be 20km h^-1

• On his return trip the average spend is 30km h^-1

$\large\sf \green { \underline{★ TO \: FIND }}$

• Averege speed for Abdul's trip

$\large\sf \blue{ \underline{★ SOLUTION}}$

• Let us assume that Abdul's travelling x kilometer distance while going to school

D = S × T

1. When its average speed is 20km/hr

$\sf{x = v_1×t_1 = 20×t_1}$

2. On returning when its average speed is 30km/hr

$\sf{x = V_2 \times t_2 = 30 \times t_2}$

$\sf{V_(average) = \frac{total \: distance}{total \: time} }$

$\sf{V_(average) = \frac{x + x}{ \frac{x}{V_1} + \frac{x}{V_2} }= \frac{2x}{ \frac{x}{20} + \frac{x}{30}} = \: 24km \: {h}^{ - 1} }$