Question

The speeds of cars passing a 20 km/h speed limit sign are recorded in the following table.
Speeds of Cars (km/h)

32	41	89	12	16	20
15	28	50	25	30	48
31	25	53	61

What is the median speed of these cars?

• A. 30.50 km/h
• B. 36 km/h

Answer 1

The correct option is A 30.50 km/h

Speeds of Cars (km/h)

32	41	89	12	16	20
15	28	50	25	30	48
31	25	53	61

To find the median of a data set, we arrange the data points from smallest to largest.

12

15

16

20

25

25

28

30

31

32

41

48

50

53

61

89

Here, the total number of data points is 16, which is an even.

$\Rightarrow$ Median is the average of the two middle values when an even number of data is arranged in ascending order.

$\therefore$ We take the average of $8^{th}$ and $9^{th}$ position data point.

The value corresponds to 8${}^{th}$ position is 30
The value corresponds to 9${}^{th}$ position is 30
$\therefore$ Median $=\frac{30+31}{2}$
$=30.50$ km/h