Question

If the mean of the observation x, x+3, x+5, x+7 and x+10 is 9, then mean of the last three observations is

Answer 1

Mean of the given five observations
` (x +(x+3) +(x+5) +(x+10))/5`
` = ((5x +25))/5= (5(x+5))/5 = (x +5)`
But, mean of these observations is 9 (given)
But , mean of these observations is 9 (given)
` x+5=9 Rightarrow x=3-5=4`
So the last three observations are (4+5),(4+7),(4+10) i.e,
9,11,14.
Mean of these observations= `((9+ 11+14))/3 = 34/3 = 11""1/3`