Question : Directions: Select the option related to the sixth number in the same way as the first number is related to the second number and the third number is related to the fourth number.
8 : 72 :: 10 : 110 :: ? : 210
Option 1: 16
Option 2: 14
Option 3: 18
Option 4: 12
Correct Answer: 14
Solution :
Given:
8 : 72 :: 10 : 110 :: ? : 210
Add 1 to the first number, and then multiply the first number by the resultant number, to obtain the second number –
Like, 8 : 72→8 × (8 + 1) = 8 × 9 = 72
And, 10 : 110→10 × (10 + 1) = 10 × 11 = 110
Similarly, follow the same pattern for ? : 210→
⇒ a × (a + 1) = 210
⇒ a
2
+ a = 210
⇒ a
2
+ a – 210 = 0
⇒ a
= –15 and a = 14
So, 14 is the required missing number. Hence, the second option is correct.
