Q.1. If the runs scored in the kth match are k. 2n+1-k and total runs scored in n matches is then the number of matches played is
Ans. 7
Let Sn = total runs scored
Q.2. The interior angles of a polygon are in arithmetic progression. The smallest angle is 120° and the common difference is 5°. Find the number of sides of the polygon.
Ans. 9
Sum of the exterior angles of a polygon is 360°.
Also the greatest exterior angle is 60°.
Q.3. If a, b, c are in H.P., then the value of is
Ans. 2
a, b, c are in H.P.
Again a, b, c are in H.P.
From (A) and (B),
Alternative solution:
We have
Q.4. Let a1,a2,....a10 be in A.P. and h1 ,h2 ,...., h10 be in H.P. If a1= h1 = 2 and a10 = h10 = 3, then a4 h7 is
Ans. 6
Q.5. Let Sn denote the sum of the first n terms of an A.P. if S2n = 3Sn , then find the value of S3n/Sn is ...
Ans. 6
Given S2n = 3Sn
Now,
Q.6. If the sum of n terms of an A.P. is 2n2 + n, then the common difference of the series is
Ans. 4
Compare the coeff of n2
d = 4
Q.7. The value of is
Ans. 4
We have,
Q.8. If the sum to infinity of the series is 44/9, then the value of d is ....
Ans. 2
Q.9. An infinite G. P. has first term x and sum 5. Then, the number of integral value of x is
Ans. 9
For finite value of | r | <1
⇒ - 5 < x - 5 < 5 ⇒ 0 < x < 10 ⇒ x has 9 integrals values.
Q.10. The largest positive term of the H.P. whose first two terms are 2/5 and 12/23 is....
Ans. 6
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