From the data given below,state which group is more variable,$A$ or $B$?

Marks	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$	$60-70$	$70-80$
Group $A$	$9$	$17$	$32$	$33$	$40$	$10$	$9$
Group $B$	$10$	$20$	$30$	$25$	$43$	$15$	$7$

(B) To determine which group is more variable,we compare their standard deviations. Since the means of both groups are equal,the group with the higher standard deviation is more variable.
For Group $A$:
Mean $\bar{x}_A = 44.6$,Variance $\sigma_A^2 = 227.84$,Standard Deviation $\sigma_A = \sqrt{227.84} \approx 15.09$.
For Group $B$:
Mean $\bar{x}_B = 44.6$,Variance $\sigma_B^2 = 243.84$,Standard Deviation $\sigma_B = \sqrt{243.84} \approx 15.61$.
Since $\sigma_B > \sigma_A$,Group $B$ is more variable.