41.
A piece of equipment cost a certain factory 6,00,000. If it depreciates in value, 15% the first year, 13.5% the next year, 12% the third year, and so on, what will be its value at the end of 10 years, all percentages applying to the original cost?

42.
What is the sum of the following series? -64, -66, -68, ......, -100

43.
What is the sum of all positive integers up to 1000, which are divisible by 5 and are not divisible by 2?

44.
If the sum of n terms of an A.P. is 3n2 + 5n then which of its terms is 164 ?

45.
The first and last term of an A.P. are a and l respectively. If S is the sum of all the terms of the A.P. and the common difference is given by $$\frac{{{l^2} - {a^2}}}{{k - \left( {l + a} \right)}}$$   then k = ?

46.
If Sn denote the sum of the first n terms of an A.P. If S2n = 3Sn , then S3n : Sn is equal to

47.
Sum of n terms of the series $$\sqrt 2 $$  $$ + $$  $$\sqrt 8 $$  $$ + $$  $$\sqrt {18} $$  $$ + $$  $$\sqrt {32} $$  $$ + $$  ....... is

48.
If the sums of n terms of two arithmetic progressions are in the ration $$\frac{{3n + 5}}{{5n + 7}},$$   then their nth terms are in the ration

50.
If 18th and 11th term of an A.P. are in the ratio 3 : 2, then its 21st and 5th terms are in the ratio