The sum of 40 A.M.’s between two number is 120. The sum of 50 A....
Let A1, A2, A3, , A40 be 40 A.M's between two numbers 'a' and 'b'.
Then,
a, A1, A2, A3, , A40, b is an A.P. with common difference d = (b - a)/(n + 1) = (b - a)/41
[ where n = 40]
now,
A1, A2, A3, , A40 = 40/2( A1 + A40)
A1, A2, A3, , A40 = 40/2(a + b)
[ a, A1, A2, A3, , A40, b is an Ap then ,a + b = A1 + A40]
sum of 40A.M = 120(given)
120= 20(a + b)
=> 6 = a + b --(1)
Again ,
consider B1, B2, B50 be 50 A.M.'s between two numbers a and b.
Then, a, B1, B2,, B50, b will be in A.P. with common difference = ( b - a)/51
now , similarly,
B1, B2, ... , B50 = 50/2(B1 + B2)
= 25(6) -from(1)
= 150