y=(1/2)-(1/3)+ (1/6)-(1/10)+(1/12)-(1/14)+(1/16)
Which of the following is best approx of Y?
1).1
2).31
3).35
4).4
5).6
AO- 2).31
Which of the following is best approx of Y?
1).1
2).31
3).35
4).4
5).6
AO- 2).31
Hi amsm25:
This is how i solved it the fastest.
Take all the plus terms and put them together and do the same with the minus terms.
Then we have Sum = 1/2 + 1/6 + 1/12 + 1/16 - (1/3 + 1/10 +1/14).
=(1/2+1/6+1/12) + 1/16 - (1/3+1/10+1/14)
= (6+2+1)/12 + 1/16 - (140 + 42 + 30)/420 (In this step i have taken the product of the denominators as the base denominator for evaluation).
= 9/12 + 1/16 - 212/420
= 3/4 + 1/16 - 0.5 (Note that half of 420 is 210, therefore 212/420 ~=0.5)
= 0.75 +0.06 - 0.5 (3/4 is 0.75 and 1/16 ~=0.06)
= 0.81 - 0.5
= 0.31
