Quantitative Aptitude - Arithmetic Ability Questions

Let the quantity of alcohol and water be 4x litres and 3x litres respectively

4x/(3x+5) = 4/5 

20x = 4(3x+5)

8x = 20

x = 2.5

Quantity of alcohol = (4 x 2.5) litres = 10 litres.

Here the given series follows a pattern that, multiplying the number with odd numbers in decreasing order starting with 13. That is,

6 × 13 = 78

65 × 11 = 858

858 × 9 = 7722

7722 × 7 = 54054

54054 × 5 = 270270

Hence, the wrong number is 54055

Friends, we know we will need gain amount to get gain percent, right. So lets get gain first.

Let the cost price of 1 pen is Re 1

Cost of 8 pens = Rs 8

Selling price of 8 pens = 12

Gain = 12 - 8 = 4

Gain% = gaincost×100%  = 48×100% = 50%

Principal = Rs100×540012×3=Rs. 15000

Here the given number series is 5  11  21  44  ?  175

Now the given series follows a pattern, that

x2 + 1, x2 - 1, x2 + 2, x2 - 2, x2 + 3, x2 - 3,...

Then the missing number is x2 - 2

= 44 x 2 - 2 = 88 - 2 = 86

Hence, the missing number in the number series is 86.

The given number series is 96, 95, 87, 78, ? 

It follows a pattern that,

$$\begin{gathered} 96 \\ 96 - 12 = 95 \\ 95 - 23 = 95 - 8 = 87 \\ 87 - 32 = 87 - 9 = 78 \\ 78 - 43 = 78 - 64 = 14 \end{gathered}$$

Hence, the next number in the given number series is 14.