Question

plz answer 19 and 20 questionmaths ch 14 class 9

Answer 1

19.
Mean of 5 numbers = 30
Mean = sum total/number of observations
Sum total of 5 = mean * number of observations = 30*5 = 150
When one number is excluded, mean = 28
Sum total of 4 = 28*4 = 112
Hence the number excluded = 150-112 = 38

20.
Mean of 100 obs = 50
Sum total of 100 obs = 100*50 = 5000
Now, 50 is replaced by 150
new total = 5000 -50 + 150 = 5100
New mean = 5100/100 = 51

Hope it helps