Quantitative Aptitude - Arithmetic Ability Questions

Sol : In this kind of questions we find the work force required to complete the work in 1 day (or given unit of time) then we equate the work force to find the relationship between the efficiencies (or work rate) between the different workers.

Therefore, 6B+8G = 6 days

 => 6(6B+8G)= 1 day  (inversely proportional)

 => 36B+48G =1         ( by unitary method)

Again  14B+10G = 4days

 => 56B+40G =1

so, here it is clear that either we employ 36B and 48G to finish the work in 1 day or 56B and 40G to finish the same job in 1 day. thus , we can say

 => 36B+48G = 56B+40G

 => G= 2.5B

Thus a Girl is 2.5 times as efficient as a boy.

Now, since  36B+48G = 1

 => 36B+48(2.5 B)=1

 =>156B=1

i.e., to finish the job in 1 day 156 boys are required or the amount of work is 156 boys-days

Again    1G+1B=2.5B+1B=3.5B

Now, since 156 boys can finish the job in 1 day

so 1 boy can finish the job in 156 days

Therefore, 3.5 boys can finish the job in 1×1563.5= 47 days.

p=(p*4*9)/100-(p*2*12)/100 = 480

=12p/100=480

p=4000

P=F1+in

Here,n = 4(children)

P(girl)= 0.5

P(of atleast one girl)= 1 - P(no girls)

                             = 1 - 0.0625 = 0.9375

12% of 70,000

=> 12 x 70,000/100

=> 8400

Hence, 12% of 70,000 = 8,400

17C2 = 136 (combination)

B runs 35 m in 7 sec.

 B covers 200 m in (7/35*200) = 40sec

B's time over the course = 40 sec.

 A's time over the course (40 - 7) sec = 33 sec.

All powers of 6 has 6 in units place so answer will definitely be 1.