Find the mean , and standard deviation for the following data :
(i) Year render:102030405060No of person (cumulative):1532517897109
(ii) Marks:2345678910111213141516Frequency:166882230210001
xiCum−Freqfifixifix2i101515150150020321734068003051195701710040782710804320050971995047500601091272043200N=109Total=3810Total=159300
Mean ¯¯¯¯¯X=3810109=34.95
Var =159300109−(34.95)2=239.96
SD = √239.96=15.49
xififixifix2i2124361854462496584020068482887214988216128932724310000112222421211214413000140001500016116256N=40Total=239Total=1753
Mean =23940=5.975
Var =175340−(5.975)2=8.12
SD = √8.12=2.85