# Exercise : 2

(b) 6

(c) 2

(d) Cannot be determined

(e) None of these

**Ans.b**

Let the four consecutive even nos. be 2x, 2x + 2, 2x + 4 and 2x + 6 respectively.

Reqd difference = 2x + 6 – 2x = 6

(b) 19

(c) 15

(d) Data inadequate

(e) None of these

**Ans.d**

Let the three consecutive odd numbers be

x – 2, x, x + 2 respectively.

According to question,

\(x = \frac{x - 2}{3} + 14\)∴ 3x – x + 2 = 42 ⇒ 2x = 40

∴ x = 20 = an even number, which goes against our supposition.

(b) 74.31

(c) 72.43

(d) 73.43

(e) Cannot be determined

**Ans.d**

Correct average = \(\frac{35 \times 72 + \left(86 - 36\right)}{35}\)

≈ 72 + 1.43 = 73.43

(b) 2

(c) 5

(d) Cannot be determined

(e) None of these

**Ans.a**

Suppose the consecutive odd numbers are : x, x + 2, x + 4, x + 6 and x + 8

Therefore, the required difference = x + 8 – x = 8

Note that answering the above question does not require the average of the five consecutive odd numbers.

(b) 4

(c) 5

(d) 6

(e) None of the above

**Ans.e**\(\frac{\left ( x + 2\right ) \times 60 + x \times 120 + \left ( x - 2 \right ) \times 180}{\left ( x + 2\right ) + x + \left ( x - 2\right )} = 100\)

⇒ \(\frac{360x - 240}{3x}\) = 100

⇒ 60x = 240 ⇒ x = 4

(b) 11

(c) 12

(d) cannot be determined

(e) None of the above

**Ans.c**

Since average price of a pencil = 2

∴ Price of 75 pencils = 150

∴ Price of 30 pens = (510 – 150) = 360

∴ Average price of a pen = ^{360}⁄_{60} = 12

(b) 52.25

(c) 51.25

(d) 53.25

(e) None of the above

**Ans.b**

Required average marks

= \(\frac{40 \times 50 + 35 \times 60 + 45 \times 55 + 42 \times 45}{40 + 35 + 45 + 42}\)

= \(\frac{2000 + 2100 + 2475 + 1890}{162}\)

= ^{8465}⁄_{162} = 52.25

(b) 1

(c) 10

(d) 19

(e) None of the above

**Ans.d**

Average of 20 numbers = 0.

∴ Sum of 20 numbers = (0 × 20) = 0.

It is quite possible that 19 of these numbers may be positive and if their sum is a, then 20th number is (–a).

(b) 4.6

(c) 4.7

(d) 4.8

(e) None of the above

**Ans.b**

Sum of the remaining two numbers

= (3.95 × 6) – [(3.4 × 2) + (3.85 × 2)]

= 23.70 – (6.8 + 7.7)

= 23.70 – 14.5 = 9.20

∴ Required average = (^{9.2}⁄_{2}) = 4.6

(b) 117

(c) 119

(d) 122

(e) None of the above

**Ans.b**

Let the average expenditure of all the nine be x.

Then, 12 × 8 + (x + 8) = 9x or 8x = 104 or x = 13.

∴ Total money spent = 9x = (9 × 13) = 117.