Quantitative Aptitude - Arithmetic Ability Questions

Given number series is 9 17 11 19 13 

Here the pattern is

• 9

• 9 + 8 = 17

• 17 - 6 = 11

• 11 + 8 = 19

• 19 - 6 = 13

• 13 + 8 = 21

• 21 - 6 = 15

• 15 + 8 = 23

Let the total number of children be x. 

Then, x * (20% of x) = 405  

=> x * 20x/100 = 405 

15x2 = 405 

=> x=45 

Number of sweets received by each child = 20% of 45 = 9.

In this type of problems the formulae is 5x-30×1211
x is replaced by the first interval of given time Here i.e 8
5*8-30*1211
= 12011min

Therefore the hands will be in the same straight line but not
together at 12011 min.past 8.

One way to deal with fractions is to convert them all to decimals. 

In this case all you would need to do is to see which is greater than 0.5.

Otherwise to see which is greater than ½, double the numerator and see if the result is greater than the denominator. In B doubling the numerator gives us 8, which is bigger than 7. 

Let the number be x, Then 

75% of x + 75 = x 

=> x - 75x/100 =75 

=> x =  300 .