Percentage

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Percentage

Question 1 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Out of the total production of iron from hematite, an ore of Iron, 20% of the ore gets wasted, and out of the remaining iron, only 25% is pure iron. If the pure iron obtained in a year from a mine of hematite was 80, 000 kg, then the quantity of hematite mined from that mine in the year is
A
4, 50, 000 kg
B
5, 00, 000 kg
C
4, 00, 000 kg
D
None of these
Question 1 Explanation: 
Let 100 kg of hematite be obtained then 20% of it get wasted that means 80 kg of ore remains.

Pure iron = 25% of remaining ore = 80*25/100 = 20 kg.

20 kg pure Iron is obtained from 100 of hematite.

1 kg pure Iron is obtained from = 100/20 hematite;

Then, 80000 kg pure Iron is obtained from = (100/20)*80000 = 400000 kg hematite.

Question 2 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
1.14 expressed as a per cent of 1.9 is:
A
90%
B
60%
C
6%
D
10%
Question 2 Explanation: 
\begin{align} & {\text{Required}}\, {\text{Percentage}} \cr & = \frac{{\left( {1.14 \times 100} \right)}}{{1.9}} \cr & = 60\% \cr\end{align}
Question 3 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The length, breadth and height of a room in the shape of a cuboid are increased by 10%, 20% and 50% respectively. Find the percentage change in the volume of the cuboid.
A
98%
B
99%
C
75%
D
77%
Question 3 Explanation: 
Let each side of the cuboid be 10 unit initially.

Initial Volume of the cuboid,

= length * breadth * height = 10 *10*10 = 1000 cubic unit.

After increment dimensions become,

Length = (10 + 10% 0f 10) = 11 unit.

Breadth = (10 + 20% of 10) = 12 unit.

Height = (10 + 50 of 10) = 15 unit.

Now, present volume = 11 *12 *15 = 1980 cubic unit.

Increase in volume = 1980 - 1000 = 980 cubic unit.

% increase in volume = (980/1000)*100 = 98%.

Mind Calculation Method:

100==50%↑(height effects)==>150==20%↑(breadth)==>180==10%↑(length effects)==>198.

Change in volume = 98%.

[We can take net percentage change in any order.]

Question 4 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In a factory there are three types of machine M1, M2 and M3 which produces 25%, 35% and 40% of the total products respectively. M1, M2 and M3 produces 2%, 4% and 5% defective products, respectively. what is the percentage of non-defective products?
A
89%
B
97.10%
C
96.1%
D
86.10%
Question 4 Explanation: 
Non-defective products M1 = 25 X 0.98 = 24.5%

Non-defective products M2 = 35 X 0.96 = 33.6%

Non-defective products M3= 40 X 0.95 = 38%

Percentage of non-defective products = 24.5 + 33.6 + 38 = 96.1%

Question 5 [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
A shepherd had n goats in the year 2000. In 2001 the no. of goats increased by 40%. In 2002 the no. of goats declined to 70%. In 2003 the no. of goats grew up 30%. In 2004, he sold 10% goats and then he had only 34, 398 goats. The percentage increase of the no. of goats in this duration was :
A
16.66%
B
14.66%
C
11.33%
D
20%
Question 5 Explanation: 
There is no need of the number of goats given i.e. 34, 398.

Initially, let there be 100 goats. Then

100 == 40% ↑==> 140 ==30%↓(declined to 70%)==> 98 ==30%↑ ==> 127.4 ==10%↓(sold)==> 114.66

Hence, % increase = 14.66% [As 100 becomes 114.66].

There are 5 questions to complete.

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