according to the given condition
a = ar + ar^2 + ar^3 + ar^4 + .......
so a = a[r/(1-r)]
here we use
"sum of infinite terms of GP = first term / [1 - common difference]"
according to the given conditions
L+M+G = 21 and G-L = 2
so G = L+2 and L+M+L+2 = 21 so 2L+M = 19 so M = 19-2L
so these three integers are L, 19-2L, L+2
possible solution is 6, 7, 8
The sum of the ages of Anup and his father is 100. When Anup will be as old as his father now, Anup will be 5 times as old as his son Anuj is now. Anuj will be eight years older than Anup is now, when Anup is as old as his father is now. What are their ages now ?
according to the given conditions
let age of Anup is a and that of father is (100-a)
according to the first condition
100-a = 5b
and on the basis of second condition [a-b]+8 = [(100-a)-a]
so b = 13 and a = 35
so answer is 13, 35, 65
distance between X and Y station is 80 km. A train covers first half with speed 50 km/hrs and second half with speed 60 km/hrs. Calculate avg speed of the journey.
OPtion
1) 55
2) 500/11
3) 400/9
4) 500/9
5) 900/7
6) 54
7) 600/11
8) 58
9) cant be calculated
10) none of these
Solution
time taken in first part = 40/50
time taken in second part = 40/60
so total time taken = 40/50+40/60 = 40[1/50+1/60] = 40*110/3000 = 44/30
so avg speed = 80/[44/30] = 2400/44 = 600/11
in 60 numbers 12 numbers will be started from each digit, since 8 comes twice 24 numbers will be started from this digit.
in these 60 numbers in every place sum of digits = 12(4+5+8+8+9) = 12*34
= 408
so sum = 408
408
408
408
408
= 4533288