CMAT Maths Puzzle Numerical Ability Sequence and Series

How many terms are there in an A.P. whose first and fifth terms are – 14 and 2, respectively and the sum of the terms is 40?
Option
(a) 15
(b) 5
(c) 10
(d) 20

Read Solution (Total 1)

ans options c)10
For the AP
a=-14
T(5)=a+(n-1)d
2=-14+(5-1)d
d=4
Sum of n terms of an AP(S)=40
S=n/2[2a+(n-1)d]
Substituing a,d and S, we get
n^2-8n-20=0
n=10
10 years agoHelpfull: Yes(2) No(0)

CMAT Other Question

Co-efficient of x in the equation x2 + px + q = 0 was wrongly written as 17 in place of 13 and the roots thus found were –2 and –15. The roots of the correct equation would be
Option
(a) 3, –10
(b) –3, –10
(c) –3, 10
(d) 3, 10 After three years, Arun would be twice as old as his brother was four years ago. His sister’s present age is half of his brother’s age that would be 12 years from now. If the sum of present ages of all the
three is twice as much as Arun’s age one year from now, his brother’s age 2 years ago would have been
Option
(a) 47 years
(b) 21 years
(c) 30 years
(d) 28 years