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.

The numbers 0,1,2,3,4,5,6,7,8,9 are 10 in number while preparing telephone numbers any number can be used any number of times.

This can be done in 105ways, but '0' is there

So, the numbers starting with '0' are to be excluded is 94 numbers.

 Total 5 digit telephone numbers = 105- 94 = 3439

Three digit number will have unit’s, ten’s and hundred’s place.

Out of 5 given digits any one can take the unit’s place.

This can be done in 5 ways. ...              (i)

After filling the unit’s place, any of the four remaining digits can take the ten’s place.

This can be done in 4 ways. ...              (ii)

After filling in ten’s place, hundred’s place can be filled from any of the three remaining digits.

This can be done in 3 ways. ... (iii) 

So,by counting principle, the number of 3 digit numbers = 5x 4 x 3 = 60

Here,n = 4(children)

P(girl)= 0.5

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

                             = 1 - 0.0625 = 0.9375

Given Loss = Rs. 40.4
We know loss = cost price - selling price
40.4 = CP - 35(15)
=> CP = 40.4 + 525
=> CP = Rs. 565.4
Now the New selling price of waffer is Rs. 18
=> SP = 35(18) = 630
Now Gain = SP - CP = 630 -565.4 = Rs. 64.6.

Ratio in which the profit will divide – 23:15. Let theprofit be P

Now, [(23/38) - (15/38)] x (60/100) x P = 500

P = 3958.34

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.

Let man invested Rs. A And, after two years amount invested = (A +