1.

Find the fourth proportional to 2.4, 4.6 and 7.6?

**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?

**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?

**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?

**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?

**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?

**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?

**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?

**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=?

**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)=?

**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 **

11.

A fraction bears the same ratio to 1/27 as 3/7 does to 5/9. The fraction is?

**Answer: Option 'B'**

**Let the fraction be x. Then,
x:1/27 = 3/7 : 5/9
x × 5/9 = 1/27 × 3/7
x × 5/9 = 1/9 × 1/7
x × 5/9 = 1/63
x × 5 = 9/63
5x = 1/7 = 1/35**

12.

The ratio of two numbers is 3:4 and their sum is 28. The greater of the two numbers is?

**Answer: Option 'D'**

**3:4
Total parts = 7
= 7 parts --> 28 (7 × 4 = 28)
= 1 part ----> 4 (1 × 4 = 4)
= The greater of the two number is = 4
= 4 parts ----> 16 (4 × 4 = 16)**

13.

The ratio of three numbers is 5:3:4 and their sum is 108. The second number of the three numbers is?

**Answer: Option 'B'**

**5:3:4
Total parts = 12
12 parts --> 108
1 part ---->9
The second number of the three numbers is = 3
3 parts ----> 27 **

14.

Three numbers are in the ratio 3:5:7. The largest number value is 42. Find difference between Smallest & largest number is?

**Answer: Option 'D'**

**= 3:5:7
Total parts = 15
= The largest number value is 42
= The largest number is = 7
= Then 7 parts -----> 42 ( 7 × 6 = 42 )
= smallest number = 3 & Largest number = 7
= Difference between smallest number & largest number is = 7 - 3 = 4
= Then 4 parts -----> 24 (4 × 6 = 24) **

15.

If two numbers are in the ratio 2:3. If 10 is added to both of the numbers then the ratio becomes 3:4 then find the smallest number?

**Answer: Option 'B'**

**2:3
2x + 10 : 3x + 10 = 3 : 4
4[2x + 10] = 3[3x + 10]
8x + 40 = 9x + 30
9x - 8x = 40 - 30
x = 10
Then smallest number is = 2
2x = 20
Short cut method:
a:b = 2:3
c:d = 3:4
1.Cross multiplication with both ratios a × d ~ b × c = 2 * 4 ~ 3 × 3 = 8 ~ 9 = 1
2. If 10 is added both the number means 10 × 3 = 30 and 10 × 4 = 40,
Then 30 ~ 40 = 10
=> 1 ---> 10
=> 2 ---> 20
**

16.

If two numbers are in the ratio 2:3. If 10 is added to both of the numbers then the ratio becomes 5:7 then find the largest number?

**Answer: Option 'D'**

**2:3
2x + 10 : 3x + 10 = 5 : 7
7[2x + 10] = 5[3x + 10]
14x + 70 = 15x + 50
15x - 14x = 70 - 50
x = 20
Then the first number is = 2
2x = 40
**

17.

If two numbers are in the ratio 5:3. If 10 is Reduced to both of the numbers then the ratio becomes 2:1 then find the smallest number?

**Answer: Option 'C'**

**5:3
5x - 10 : 3x - 10 = 2 : 1
1[5x - 10] = 2[3x - 10]
5x - 10 = 6x - 20
6x - 5x = 20 - 10
x = 10
the small number is = 3
3x = 30 (Answer = 30)
**

18.

A mixture contains milk and water in the ratio 5:2. On adding 10 liters of water, the ratio of milk to water becomes 5:3. The quantity of milk in the original mixture is?

**Answer: Option 'A'**

**milk:water = 5:2
5x : 2x + 10 = 5 : 3
3[5x] = 5[2x + 10]
15x = 10x + 50
15x - 10x = 50
x = 10
The quantity of milk in the original mixture is = 5 : 2 = 5 + 2 = 7
7x = 70
**

19.

A mixture contains milk and water in the ratio 7:3. On adding 20 liters of water, the ratio of milk to water becomes 7:5. Total quantity of milk & water before adding water to it?

**Answer: Option 'B'**

**milk:water = 7:3
7x : 3x + 20 = 7 : 5
5[7x] = 7[3x + 20]
35x = 21x + 140
35x - 21x = 140
14x = 140
x = 10
The quantity of milk in the original mixture is = 7 : 3 = 7 + 3 = 10
10x = 100
**

20.

A mixture contains milk and water in the ratio 3:2. On adding 10 liters of water, the ratio of milk to water becomes 2:3. Total quantity of milk & water before adding water to it?

**Answer: Option 'C'**

**milk:water = 3:2
after adding 10 liters of water
milk:water = 2:3
Olny water patrs increase when mixture of water
milk:wate = 3:2 = 2*(3:2) = 6:4
after adding 10 liters of water
milk:water = 2:3 = 3*(2:3) = 6:9
milk parts always same
**

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