Question

A car travels 20 km in first hour,40 km in second hour and 30 km in third hour. Calculate the average speed of the train.
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Answer 1

Answer: The average speed of the train is 30 km per hour.

Explanation:

To find the average of a set of numbers, you need to add up all the numbers and then divide by the amount of numbers.

In this case 20+30+40=90

Since there are 3 numbers you divide 90 by 3 and get 30.

Answer 2

Given :

▪ Distance covered in first hour = 20km

▪ Distance covered in second hour = 40km

▪ Distance covered in third hour = 30km

To Find :

▪ Average speed of the train.

Concept :

✏ Average speed is defined as the ratio of total distance travelled to the total time taken.

✏ It is a scalar quantity.

✏ It has only magnitude.

✏ It can't be negative/zero.

✏ SI unit : m/s

Calculation :

$\dashrightarrow\sf\:v_{av}=\dfrac{d_1+d_2+d_3}{t_1+t_2+t_3}\\ \\ \dashrightarrow\sf\:v_{av}=\dfrac{20+40+30}{1+1+1}\\ \\ \dashrightarrow\sf\:v_{av}=\dfrac{90}{3}\\ \\ \dashrightarrow\underline{\boxed{\bf{\gray{v_{av}=30kmph}}}}\:\blue{\bigstar}$