Quantitative Aptitude - Arithmetic Ability Questions

The given number series follows a pattern that

11

11 - 5.5 = 5.5

5.5 + 4.5 = 10

10 - 3.5 = 6.5

6.5 + 2.5 = 9

9 - 1.5 = 7.5

Hence, the next number in the given number series is 7.5.

The word 'OPTICAL' contains 7 different letters.

When the vowels OIA are always together, they can be supposed to form one letter.

Then, we have to arrange the letters PTCL (OIA).

Now, 5 letters can be arranged in 5! = 120 ways.

The vowels (OIA) can be arranged among themselves in 3! = 6 ways.

Required number of ways = (120 x 6) = 720.

The given number series 11, 13, 30, 96, ? follows a pattern that,

11

11 x 1 + 2 = 13

13 x 2 + 4 = 30

30 x 3 + 6 = 96

96 x 4 + 8 = 392

Hence, the next number in the given series is 392.

Total volume of water displaced =(4 x 50) cu.m = 200 cu.m

Rise in water level = 20040×20=0.25m = 25cm

Let the original number be x.

Final number obtained = 110% of (90% of x) =(110/100 * 90/100 * x) = (99/100)x. 

x-(99/100)x=10

=> x =1000

The given number series is 3, 11, 80, 291, 803

$$\begin{gathered} 3 \\ 3 + 23 = 3 + 8 = 11 \\ 11 + 43 = 11 + 64 = 75 (not 80) \\ 75 + 63 = 75 + 216 = 291 \\ 291 + 83 = 291 + 512 = 803 \end{gathered}$$