Question: 16 -
A bag contains Rs 410 in the form of Rs 5, Rs 2, and Rs 1 coins. The number of coins is in the ratio 4: 6: 9. So, find the number of 2 Rupees coins.
-
70
-
60
-
50
-
40
Answer:
60
Solution:
ATQ, if the ratio of coins = 4: 6: 9
That means if Rs 5 coins are 4, Rs 2 coins are 6, and then Rs 1 coins are 9.
According to the given ratio, the ratio of amounts = 5*4: 6*2: 9*1 = 20: 12: 9
The sum of the ratios of the amounts = 20+12+9 = Rs 41
But ATQ, it is Rs 410, which means multiply each ratio by 10
i.e., new ratio = 40: 60: 90
Now, 40*5: 60*2: 90*1 = 200: 120: 90
The total amount in the form of two rupees coins = 120
So, the two rupees coins = 120/2= 60
ATQ, if the ratio of coins = 4: 6: 9
That means if Rs 5 coins are 4, Rs 2 coins are 6, and then Rs 1 coins are 9.
According to the given ratio, the ratio of amounts = 5*4: 6*2: 9*1 = 20: 12: 9
The sum of the ratios of the amounts = 20+12+9 = Rs 41
But ATQ, it is Rs 410, which means multiply each ratio by 10
i.e., new ratio = 40: 60: 90
Now, 40*5: 60*2: 90*1 = 200: 120: 90
The total amount in the form of two rupees coins = 120
So, the two rupees coins = 120/2= 60
Question: 17 -
The ratio of land and water on earth is 1: 2. In the northern hemisphere, the ratio is 2: 3. What is the ratio in the southern hemisphere?
-
3:11
-
2:11
-
1:11
-
4:11
Answer:
4:11
Solution:
The ratio of land: water = 1: 2
In the northern hemisphere the ration of land: water = 2: 3
Note: Earth is divided equally into two hemispheres called northern hemisphere and southern hemisphere.
i.e., the northern hemisphere is 50% of the total earth.
We can say southern hemisphere = total area- northern hemisphere.
To make the northern hemisphere 50% of the total area
Multiply the ratio of the earth by 10 and northern hemisphere by 3
Now, earth's ratio Land: water = 1*10: 2*10 = 10: 20............... (i)
Northern hemisphere's ratio = 2*3: 3*3 = 6: 9...................... (ii)
Subtract equation i by ii
Hence, southern hemisphere = 10- 6: 20-9 = 4: 11
The ratio of land: water = 1: 2
In the northern hemisphere the ration of land: water = 2: 3
Note: Earth is divided equally into two hemispheres called northern hemisphere and southern hemisphere.
i.e., the northern hemisphere is 50% of the total earth.
We can say southern hemisphere = total area- northern hemisphere.
To make the northern hemisphere 50% of the total area
Multiply the ratio of the earth by 10 and northern hemisphere by 3
Now, earth's ratio Land: water = 1*10: 2*10 = 10: 20............... (i)
Northern hemisphere's ratio = 2*3: 3*3 = 6: 9...................... (ii)
Subtract equation i by ii
Hence, southern hemisphere = 10- 6: 20-9 = 4: 11
Question: 18 -
Rs 7800 are distributed among A, B, and C. The share of "A" is the ¾ of the share of B, and the share of B is the 2/3 of the share of C. Find the difference between the share of B and C.
-
1200
-
1250
-
800
-
1300
Answer:
1200
Solution:
The share of A: B is 3: 4
The share of B: C is 2: 3
Note: Whenever such form is given, multiply a to b, then b to b, and then b to c.
i.e., A: B: C = 3*2: 4*2: 4*3
Or, A: B: C = 6: 8: 12
Or, A: B: C = 3: 4: 6
Sun of ratios = 13
Now, the share of B = [4/13] * 7800 = 2400
Share of C = [6/13]* 7800 = 3600
The difference between the share of B and C = 3600- 2400 = 1200
The share of A: B is 3: 4
The share of B: C is 2: 3
Note: Whenever such form is given, multiply a to b, then b to b, and then b to c.
i.e., A: B: C = 3*2: 4*2: 4*3
Or, A: B: C = 6: 8: 12
Or, A: B: C = 3: 4: 6
Sun of ratios = 13
Now, the share of B = [4/13] * 7800 = 2400
Share of C = [6/13]* 7800 = 3600
The difference between the share of B and C = 3600- 2400 = 1200
Question: 19 -
The ratio of copper and zinc in a 63 kg alloy is 4: 3. Some amount of copper is extracted from the alloy, and the ratio becomes 10: 9. How much copper is extracted?
-
6
-
8
-
10
-
12
Answer:
6
Solution:
Amount of copper in alloy = [copper ratio/ sum of ratios]* total quantity of alloy
Copper = {4/7}* 63 = 36 kg
Similarly, the amount of zinc in alloy = [3/7] * 63 = 27 kg
Let the extracted copper from alloy = x kg
Remaining copper in alloy = 36-x
The new ratio = 10: 9
i.e., 36-x: 27 = 10: 9
36-x: 3 = 10: 1
36-x = 10* 3
36-x = 30
x = 36-30 = 6 kg.
Hence, the extracted amount of copper is 6 kg.
Amount of copper in alloy = [copper ratio/ sum of ratios]* total quantity of alloy
Copper = {4/7}* 63 = 36 kg
Similarly, the amount of zinc in alloy = [3/7] * 63 = 27 kg
Let the extracted copper from alloy = x kg
Remaining copper in alloy = 36-x
The new ratio = 10: 9
i.e., 36-x: 27 = 10: 9
36-x: 3 = 10: 1
36-x = 10* 3
36-x = 30
x = 36-30 = 6 kg.
Hence, the extracted amount of copper is 6 kg.
Question: 20 -
B is inversely proportional to the cube of A. If B=3, A=2. If B = 8/9. Find the value of A.
-
3
-
6
-
4
-
5
Answer:
3
Solution:
As per the question, B is inversely proportional to A3
i.e., B α 1/A3
Or, B =k/ A3
Given that, B=3, A=2
So, 3 = k/ 8, or k=24
Given that, B = 8/9
So, 8/9 = 24/A3
A3 = (9*24)/8 = 27
So, A = 3√ 27 = 3
As per the question, B is inversely proportional to A3
i.e., B α 1/A3
Or, B =k/ A3
Given that, B=3, A=2
So, 3 = k/ 8, or k=24
Given that, B = 8/9
So, 8/9 = 24/A3
A3 = (9*24)/8 = 27
So, A = 3√ 27 = 3