# Exercise : 6

47^{7.5} ÷ 47^{3⁄2} × 47^{-3} = (√47)^{?}

(b) 2

^{1}⁄

_{2}

(c) 6

(d) 3.5

(e) None of these

**Ans.c**

(47)^{3} = [(47)^{1/2}]^{6}

33^{1}⁄_{3}% of 768.9 + 25% of 161.2 – 68.12 = ?

(b) 225

(c) 235

(d) 220

(e) 240

**Ans.a**

? = 33^{1}⁄_{3}% of 768.9 + 25% of 161.2 – 68.12

= ^{1}⁄_{3} of 768.9 + ^{1}⁄_{4} of 161.2 – 68.12

= 256.3 + 40.3 – 68.12 ≈ 230

(b) 10^{3} – 100 × 7

(c) 5\(\sqrt{3600}\)

(d) 450 ÷ 50 × 50 – 5 × 30

(e) 10 × 3 + 120 × 2

**Ans.e**

Other parts are equal to 300.

(b) 2207.1 ÷ 21

(c) 16

^{2}⁄

_{3}% of 630.6

(d) 32.84375 × 3.2

(e)

^{1}⁄

_{5}of

^{1}⁄

_{9}of 4729.4

**Ans.e**

The other parts are equal to 105.10.

^{2}– 3xy + y

^{2}

(b) (2x + y)(x – y)

(c) (x – y)

^{2}+ x(x – y)

(d) (2x – y)

^{2}– x(2x – y)

(e) (2x – y)

^{2}– 2x

^{2}+ xy

**Ans.b**

Other parts are equal to

2x^{2} + y^{2} – 3xy.

(b) 98 ÷ 2.5 + 15.2 × 4

(c) \(\sqrt{225}\) – 5 × 2

^{2}

(d) 76 × 1.5 – 5.5 × 2.6

(e) 48 × 1.2 + 127.2 ÷ 3

**Ans.d**

Check all options one by one.

(a) \(\frac{75 \times 8}{6} = 100\)

(b) ^{98}⁄_{2.5} + (15.2 × 4) = 100

(c) (15 × 8) – (5 × 4) = 100

(d) (76 × 1.5) – (5.5 × 2.6) = 99.7

(e) (48 × 1.2) + ^{127.2}⁄_{3} = 100

(b) 425 ÷ 17 × 4

(c) 36 × 5 ÷ 6 + 17 × 4

(d) 2

^{6}+ \(\sqrt{256}\) + 20

(e) 35 × 12 ÷ 14 + 14 × 5

**Ans.c**

All others are equal to 100. But option (c) gives a value equal to 98.

^{2}× 10

(b) 113 × 25 × 2

(c) 27 × 25 × 8 + 15 × 6 + 4 × 40

(d) 226 × 5 + 113 × 45 =

(e) 50

^{2}× 2 + 13 × 50

**Ans.d**

Others equal 5650.

(b) 45 × 6 + 75 × 4

(c) 175 ÷ 25 × 75 + 5

^{2}

(d) 36 × 4 + 21

^{2}– 7 × 5

(e) 65 × 12 – 46 × 5

**Ans.b**

Except it, others are equal to 550.

(b) 10% of 5000 +

^{2}⁄

_{5}of 1200

(c) 80 × 40 – 20 × 110

(d) 8640 ÷ 60 + 53.5 × 16

(e) 5314 – 3029 – 1285

**Ans.b**

The other parts are equal to 1000.