Practice Consecutive numbers - quantitative aptitude Online Quiz (set-1) For All Competitive Exams
Q-1) Average of first five odd multiples of 3 is
(a)
(b)
(c)
(d)
Using Rule 1,
Average of numbers = ${x_1+x_2+…+x_n}/n$
Average of first five odd multiples of 3
= ${3(1+3+5+7+9)}/5$
= ${3×25}/5$ = 15
Q-2) The average of four consecutive even numbers is 15. The 2nd highest number is
(a)
(b)
(c)
(d)
x + x + 2 + x + 4 + x + 6 = 15 × 4
⇒ 4x + 12 = 60
⇒ 4x = 60 – 12 = 48
⇒ x = $48/4$ = 12
Hence, the numbers are 12, 14, 16, 18
∴ The second highest number is 16.
Q-3) The average of nine consecutive odd numbers is 53. The least odd number is
(a)
(b)
(c)
(d)
x + x + 2 + x + 4 + x + 6 + x +
8 + x + 10 + x + 12 + x + 14 + x + 16 = 9 × 53
⇒ 9x + 72 = 477
⇒ 9x = 477 – 72 = 405
⇒ x = $405/9$ = 45
Q-4) The average of four consecutive even numbers is 9. Find the largest number.
(a)
(b)
(c)
(d)
x + x + 2 + x + 4 + x + 6 = 9 × 4
⇒ 4x + 12 = 36
⇒ 4x = 36 – 12 = 24
∴ x = $24/4$ = 6
∴ Largest number = 6 + 6 = 12
Q-5) If the average of 6 consecutive even numbers is 25, the difference between the largest and the smallest number is
(a)
(b)
(c)
(d)
Numbers = x, x + 2, ...., x + 10 Required difference
= x + 10 – x = 10
Q-6) The average of all the odd integers between 2 and 22 is:
(a)
(b)
(c)
(d)
Required average
= ${3+5+7+9+11+13+15+17+19+21}/10$
= $120/10$ = 12
Q-7) What is the average of the first six (positive) odd numbers each of which is divisible by 7?
(a)
(b)
(c)
(d)
Required average
= ${7+21+35+49+63+77}/6$
= ${7(1+3+5+7+9+11)}/6$
= ${7×36}/6$ = 42
Q-8) The average of 7 consecutive numbers is 20. The largest of these numbers is :
(a)
(b)
(c)
(d)
Average of 7 consecutive numbers is 20.
Since the numbers are consecutive, they form an arithmetic series with common difference 1.
Since, 7 is odd, 20 must be the middle number.
We can write the series as below,
17, 18, 19, 20, 21, 22, 23
∴ The largest of these numbers is 23.
Q-9) The average of 7 consecutive numbers is 20. The largest of these numbers is
(a)
(b)
(c)
(d)
Average of 7 consecutive numbers = 20
∴ Fourth number = 20
∴ Largest number = 20 + 3 = 23
Q-10) The sum of three consecutive even numbers is 28 more than the average of these three numbers. Then the smallest of these three numbers is
(a)
(b)
(c)
(d)
Let three consecutive even numbers be x, x + 2 and x + 4. According to the question,
(x + x + 2 + x + 4) – ${x+x+2+x+4}/3$= 28
⇒ (3x + 6) – ${3x+6}/3$ = 28
⇒ (3x + 6) – (x + 2) = 28
⇒ 3x + 6 – x – 2 = 28
⇒ 2x + 4 = 28
⇒ 2x = 28 – 4 = 24
⇒ x = $24/2$ = 12