Number Series Completion - Study Mode

[#76] Find the missing number: 2 / √5 , 3 / 5 , 4 / 5√5 , 5 / 25 , ?
Correct Answer

(B) 6 / 25√5

Explanation

Solution: Clearly, the numerators of the given fractions are consecutive natural numbers. So, the numerator of the missing fraction should be 6. Also, the denominator of each fraction is multiplied by √5 to obtain the denominator of the next fraction. So. the denominator of the missing fraction should be 25√5. Hence,the missing term is 6 / 25√5

[#77] In the series 2, 6, 18, 54, ...., what will be the 8th term ?
Correct Answer

(B) 4374

Explanation

Solution: Clearly, 2 × 3 = 6, 6 × 3 = 18, 18 × 3 = 54,.............. S, the series is a G.P. in which a = 2, r = 3 ∴8th term = ar (8 - 1) = ar 7 = 2 × 3 7 = (2 × 2187) = 4374

[#78] Find the missing term: 2, 1, 2, 4, 4, 5, 6, 7, 8, 8, 10, 11, ?
Correct Answer

(B) 10

Explanation

Solution: The given sequence is a combination of three series: I. 1st, 4th, 7th, 10th, 13th terms i.e., 2, 4, 6, 8, ? II. 2nd, 5th, 8th, 11th terms i.e., 1, 4, 7, 10 III. 3rd, 6th, 9th, 12th terms i.e., 2, 5, 8, 11 Clearly, I. consists of consecutive even numbers. So, the missing term is 10.

[#79] Find the missing number: 11 1 / 9 , 12 1 / 2 , 14 2 / 7 , 16 2 / 3 , ?
Correct Answer

(C) 20

Explanation

Solution: The given sequence is 100 / 9 , 25 / 2 , 100 / 7 , 50 / 3 , ............i.e., 100 / 9 , 100 / 8 , 100 / 7 , 100 / 6 ................. So, missing term = 100 / 5 = 20

[#80] Find the missing term: 8, 9, 8, 7, 10, 9, 6, 11, 10, ?, 12
Correct Answer

(A) 5

Explanation

Solution: The given sequence is a combination of three series: I. 1st, 4th, 7th, 10th, terms i.e., 8, 7, 6, ? II. 2nd, 5th, 8th, 11th terms i.e.,9, 10, 11, 12 III. 3rd, 6th, 9th, terms i.e., 8, 9, 10 The pattern in I. is - 1 So, the missing term is = 6 - 1 = 5