Question

1. A girl moves with a speed of 6 km/hr for 2 hours and with a speed of 4 km/hr for the
next 3 hours. Find the average speed of the girl and total distance. ​

Answer 1

$\underline{\sf{\bigstar\ Given:-}}$

$\bullet\sf \ speed_1= 6km/h\ \ ; \ \bullet\ Time_1= 2hours\\ \\ \\ \bullet\sf\ speed_2= 4km/h\ \ ; \ \bullet\ Time_2=3hours$

$\underline{\sf{\bigstar\ To\ Find :-}}$

• We have to find the average speed of girl & Total distance covered by the Girl !

$\underline{\bigstar{\sf\ According\ to \ Formula :-}}$

First find the distance

$\sf\ Speed = \dfrac{Distance }{Time}\\ \\ \longrightarrow\sf S_1= \dfrac{D_1}{T_1}\\ \\ \longrightarrow\sf 6= \dfrac{d_1}{2}\\ \\ \longrightarrow\sf 12=d_1 --------(i)$

Now distance covered in 2nd part

$\longrightarrow\sf S_2= \dfrac{D_2}{T_2}\\ \\ \longrightarrow\sf 4= \dfrac{d_2}{3}\\ \\ \longrightarrow\sf 12=d_2--------(ii)$

Now ,

• Total distance = Equation (i) + Equation (ii)

Total distance = 12+12= 24 km

Now find the Average speed !

$\boxed{\sf\ Average \ speed = \dfrac{Total \ distance }{Total \ Time}}$

$\longrightarrow\sf Av. \ speed = \dfrac{d_1+d_2}{t_1+t_2}\\ \\ \longrightarrow\sf Av. \ speed = \dfrac{24}{2+3}\\ \\ \longrightarrow\sf Av.\ speed = \cancel{\dfrac{24}{5}}\\ \\ \longrightarrow\sf Av.\ speed = 4.8km/h$

$\underline{\bigstar{\sf\ Average\ speed = 4.8km/h}}$

$\underline{\bigstar{\sf\ Total \ Distance= 24km}}$

Answer 2

Answer :

Given -

• Speed = 6 km/hr
• Time period = 2 hr
• Speed for the next 3 hrs is 4 km/hr

To Find -

• Average speed
• Total Distance

Solution -

For the first case :

• Distance = d1
• Speed = 6 km/hr.
• Time = 2 hours

Speed = Distance/Time

➸ 6 = d1/2

➸ d1 = 12 km

For the second case :

• Distance = d2
• Speed = 4 km/hr
• Time = 3 hours

➸ 4 = d2/3

➸ d2 = 12 km

Now, Finding the Average speed :

Average Speed = Total Distance/Total Time

➸ Average Speed = (12 + 12)/(2 + 3)

➸ Average Speed = (24)/(5)

➸ Average Speed = 4.8 km/hr

Hence,

Final Answers :

• Total Distance = 12 + 12 = 48 km
• Average Speed = 4.8 km/hr