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- 1. Find the fourth proportional to 2.4, 4.6 and 7.6?

A.) 14

B.) 14.657

C.) 15.56

D.) 14.56

Answer: Option 'D'

Formula = Fourth propotional = (b × c)/a

A = 2.4 , B = 4.6 and C = 7.6

(4.6 × 7.6)/2.4 = 14.56

- 2. Find the third proportional to 9 and 12?

A.) 9

B.) 108

C.) 16

D.) 9

Answer: Option 'C'

Formula = Third proportional = (b × b)/a

A = 9 and B = 12

(12 × 12)/ 9 = 144/9 = 16

- 3. Find the mean proportional between 49 & 81?

A.) 16

B.) 10

C.) 63

D.) 12

Answer: Option 'C'

Formula = √a×b

A = 49 and B = 81

√49×81 = 7 × 9 = 63

- 4. Find the fourth proportional to 0.2,0.12 and 0.3?

A.) 0.13

B.) 0.18

C.) 0.8

D.) 0.15

Answer: Option 'B'

Formula = Fourth propotional = (b × c)/a

A = 0.2 , B = 0.12 and C = 0.3

(0.12 × 0.3)/0.2

0.036/0.2 = 0.18

- 5. If a:b=1:2 and b:c=3:4 find a:b:c?

A.) 3:8:6

B.) 3:12:6

C.) 3:6:8

D.) 1:2:4

Answer: Option 'C'

a:b = 1:2, b:c = 3:4

1:2

3:4

(a = 1 × 3 = 3, b = 2 × 3 = 6 and c = 2 × 4 = 8)

(a = a × b, b = b × b and c = b × c)

a:b:c = 3:6:8

- 6. If a:b=1:2, b:c=3:4 and c:d = 2:3 find a:b:c:d?

A.) 3:6:8:24

B.) 6:12:16:24

C.) 6:18:24:16

D.) 3:6:2:3

Answer: Option 'B'

a:b = 1:2, b:c = 3:4, c:d = 2:3

1:2

3:4

( a = 1 × 3 = 3, b = 2 × 3 = 6 and c = 2 × 4 = 8)

(a = a × b, b= b × b and c= b × c)

a:b:c = 3:6:8

a:b:c = 3:6:8 and c:d = 2:3

(Note: First a,b,c multiplication with c means 2 and last c means 8

multiplication with d means 3

a:b:c:d = 6:12:16:24

- 7. If a:b=2:3, b:c=4:5 and c:d=4:2 find a:b:c:d?

A.) 32:48:8:24

B.) 8:12:60:24

C.) 32:18:24:30

D.) 32:48:60:30

Answer: Option 'D'

a:b = 2:3, b:c = 4:5, c:d = 4:2

2:3

4:5

( a = 2× 4 = 8, b = 37 × 4 = 12 and c = 3 × 5 = 15)

(a = a × b, b = b × b and c = b × c)

a:b:c = 8:12:15

a:b:c = 8:12:15 and c:d = 4:2

(Note: First a=8,b=12,c=15 multiplication with c means 4 and last c = 15

multiplication with d means 2

a:b:c:d = 32:48:60:30

- 8. If 2a=6b and 9b=7c, Find a:b:c?

A.) 42:18:14

B.) 3:9:7

C.) 9:27:22

D.) 21:7:9

Answer: Option 'D'

(2a = 6b => a/b = 6/2)

and (9b = 7c => b/c = 7/9)

=> a:b = 6:2 and b:c = 7:9

a:b:c = 42:14:18 = 21:7:9

- 9. If 0.4:1.4 :: 1:4:x, then x=?

A.) 49

B.) 4.9

C.) 0.49

D.) 0.4

Answer: Option 'B'

0.4 × x = 1.4 × 1.4

x = 1.4 × 1.4/0.4 = 14/10 × 14/10 × 1/(4/10)

14/10 × 14/10 × 10/4

7/10 × 7 = 49/10 = 4.9

- 10. If x:y=5:3 then (8x-5y) : (8x+5y)=?

A.) 5:13

B.) 13:5

C.) 5:11

D.) 11:5

Answer: Option 'C'

x/y = 5/3 (Given)

(8x − 5y)/(8x + 5y)

8(x/y) − 5/8(x/y)+5

( on dividing Nr and Dr by y)

(8(5/3) − 5)/(8(5/3) + 5)

(40/3 − 5/1)/(40/3 + 5/1)

[(40 − 15)/3]/[(40 + 15)/3]

25/55 = 5/11

(8x-5y):(8x+5y) = 5:11

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