Advertisements
Advertisements
प्रश्न
A number is increased by 25% and then decreased by 20%. Find the percentage change in that number
उत्तर
Method 1:
Let the number be x.
First it is increased by 25%
∴ It becomes `x + 25/100 xx x = 125/100`
Secondary it is decreased by 20%
`125/100x - 20/100 xx 125/100x = 125/100x xx 80/100` = x
Now we get back x, therefore there is no change.
Hence percentage change in that number is 0%
Method 2:
To understand, let us assume that number is 100
So, first when we increase by 25%, we get
`100 + 25/100 xx 100` = 100 + 25 = 125
Now this 125 is decreased by 20%, we get
`125 - 20/100 xx 125` = 125 – 25 = 100
∴ We get back 100 ⇒ No change
Hence percentage change in that number is 0%
APPEARS IN
संबंधित प्रश्न
Evaluate : 9.3% of 500 – 4.8% of 250 – 2.5% of 240
A man spends 87% of his salary. If he saves Rs. 325; find his salary.
Express the following percentage as a fraction and as a decimal number:
25 %
What percent is: 25 cm of 4 metres
70% of our body weight is made up of water. Find the weight of water in the body of a person whose body weight is 56 kg.
The original price of an article is ₹ 640. Find its new price when its price is increased by 30%
Air is an important inexhaustible natural resource. It is essential for the survival of human beings, microbes, plants, and animals. The following table shows the percentage of various gases in the air.
| Contents of air | Percentage (by volume) |
| Nitrogen | 78 |
| Oxygen | 21 |
| Other (carbon dioxide, inert gases, water vapours, etc.) | 1 |
In 800 m3 of air, calculate the approximate quantities of nitrogen, oxygen, and other gases.
There are 500 students in a rural school. If 370 of them can swim, what percentage of them can swim and what percentage cannot?
In Delhi University, in the year 2009 – 10,49,000 seats were available for admission to various courses at graduation level. Out of these 28,200 seats were for the students of General Category while 7,400 seats were reserved for SC and 3,700 seats for ST. Find the percentage of seats available for students of SC Category and ST Category taken together.
Below is the Report Card of Vidit Atrey. Vidit’s teacher left the last column blank. Vidit is not able to make out, in which subject he performed better and in which he needs improvement. Complete the table to help Vidit know his comparative performance.
| Assessment Report for 2009-2010 | |||||
| Class : 9B | Name : Vidit Atrey | Date : 31 March 2010 | |||
| Subject | Internal assessment |
Examination | Total | Final% | |
| 1. | English Literature | 20/25 | 82/100 | 102/125 | |
| 2. | English Language | 22/25 | 91/100 | 113/125 | |
| 3. | Hindi Literature | 18/25 | 67/75 | 85/100 | |
| 4. | Hindi Language | 16/25 | 68/75 | 84/100 | |
| 5. | Mathematics | 42/50 | 88/100 | 130/150 | |
| 6. | Sanskrit | 14/20 | 75/100 | 99/120 | |
| 7. | Physics | 45/50 | 90/100 | 135/150 | |
| 8. | Chemistry | 41/50 | 82/100 | 123/150 | |
| 9. | Biology | 43/50 | 87/100 | 130/150 | |
| 10. | History and Civics | 19/25 | 68/75 | 87/100 | |
| 11. | Geography | 17/20 | 71.5/80 | 88.5/100 | |
