Question

Frequency distribution of distance travelled( in km) per litre of petrol by different mopeds is given below.

Distance travelled (in km)	62-65	65-68	68-71	71-74	74-77	77-80	80-83
No. of mopeds	5	8	12	28	35	10	2

Find the mean distance travelled per litre of petrol by a moped.

Answer 1

Distance travelled (in km) Class Intervals	Class Marks $\left(x_i\right)$	No. of mopeds $\left(f_i\right)$	$\left(f_i\right)$$\left(x_i\right)$
62-65	63.5	5	317.5
65-68	66.5	8	532
68-71	69.5	12	834
71-74	72.5	28	2030
74-77	75.5	35	2642.5
77-80	78.5	10	785
80-83	81.5	2	163
Total	-	$\sum _{}^{}{f}_i=100$	$\sum _{}^{}{f}_i{x}_i=7304$

$\mathrm{Mean}=\overline{x}=\frac{{\displaystyle \sum _{}^{}}{f}_i{x}_i}{{\displaystyle \sum _{}^{}}{f}_i}=\frac{7304}{100}=73.04$

Therefore, mean distance travelled per litre of petrol by a moped is 73.04 km.