List of top Mathematics Questions on Variance and Standard Deviation asked in BITSAT

The variance of 20 observations is 5. If each observation is multiplied by 2, then the new variance of the resulting observation is

Find the variance of the data given below \[ \text{Size of item:} \quad 3.5, 4.5, 5.5, 6.5, 7.5, 8.5, 9.5 \\ \text{Frequency:} \quad 3, 7, 22, 60, 85, 32, 8 \]

Find the variance of the data given below

Occurance $(x_i)$	Frequency $(f_i)$	Freq $\ast (x_i)$	$(x_i-mean)$	$(x_i-mean)^2$	$f_i(x_i-mean)^2$
3.5	3	10.5	-3.59	12.887	38.661
4.5	7	31.5	-2.59	6.707	46.952
5.5	22	121	121	2.528	55.609
6.5	60	390	-0.59	0.348	20.876
7.5	85	637.5	0.41	0.168	14.298
8.5	32	272	1.41	1.988	63.632
9.5	8	76	2.41	5.809	46.47
Total	217	1538.5	-	-	286.498

If sample A contains 100 observations 101, 102, .... 200 and sample B contains 100 observations 151, 152, .... 250, then the ratio of variance \( \frac{V_A}{V_B} \) is: