model 2 average of consecutive numbers Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (d)

m + m + 1 + m + 2 + m + 3 + m + 4 = 5n

⇒ 5m + 10 = 5n

⇒ m + 2 = n ....(i)

Required average = ${m+2+m+3+m+4+m+5+m+6+m+7}/6$

= ${6m+27}/6$

= ${2m+9}/2$ = ${2(n-2)+9}/2$= ${2n+5}/2$ By (i) [m = n – 2]

Answer: (c)

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.

Answer: (b)

If the smallest number be x, then

$x/3$+12 = x+2

⇒ x + 36 = 3x + 6

⇒ 3x – x = 36 – 6

⇒ 2x = 30 ⇒ x = 15

∴ Third number = 15 + 4 = 19

Answer: (d)

Required average

= ${7+21+35+49+63+77}/6$

= ${7(1+3+5+7+9+11)}/6$

= ${7×36}/6$ = 42

Answer: (c)

Required average

= ${2+3+5+7+11}/5$

= $28/5$ = 5.6

Answer: (c)

Required average

= ${3+5+7+9+11+13+15+17+19+21}/10$

= $120/10$ = 12