Page 137 - Start Up Mathematics_7

EXERCISE 8.2

1. The monthly salary of a teacher is ` 12,800. If his annual increment is 3%, find his new
salary after an year.
2. Amina buys a book for ` 275 and sells it at a loss of 15%. How much does she sell it for?
3. In a public examination 90% students passed and 8,800 students failed. How many students
appeared and how many passed?

4. A basket contains 360 pears. Due to poor weather conditions about 15% pears got spoilt.
Find the number of good pears.
5. 2% commission on sale of a property equals ` 4,240. What is the value of the property?
6. ` 6,000 is borrowed at 8% rate of interest p.a. Find the interest and amount after 3 years.
7. Divya borrows a sum of ` 1,200 at the rate of 5% p.a. After how many years does she pay
back the money if the interest paid is ` 120?

Project Work

Use of percentage in daily life
Conduct a survey and find the time spent by the students of your class in the following
activities. Categorize them on the basis of time spent and fill the table given below:
(a) The number of hours spent per day by each student in studying or completing the
homework.

(b) The number of hours spent per day by each student on computer.

Number of hours Name of the students Total number Percentage of students
spent per day (or Tally Bars) of students (x) x × 100
y
Upto 1 hour

Between 1 hour
to 2 hours
Greater than or
equal to 2 hours
Grand total y = ................ ............................
Note: Use the above table for both (a) and (b).
Answer the following questions:

1. What percentage of students spend more than an hour on computers?
2. What time duration is spent by the maximum number of students in studying or doing
their homework?
3. Is the argument valid that students who spend more time on computers study less?
4. What percentage of students devote between 1 to 2 hours to studies (including
homework) and what percentage of students spend the same time, i.e., 1 to 2 hours
on computers? Which one is greater and by what percent?
5. What is the grand total of percentages of students spending different time on computers?
Is it 100%?

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