Question
A sum of money amounts to Rs 8400 in 3 years and Rs 9000
in 4 years at simple interest. Find the principal and the rate of interest per annum.Solution
Interest for the 4th year = 9000 − 8400 = Rs 600. So, simple interest per year = Rs 600. In 3 years, total interest = 3 × 600 = Rs 1800. Therefore principal = amount after 3 years − interest = 8400 − 1800 = Rs 6600. Rate of interest = (SI for 1 year / Principal) × 100 = (600 / 6600) × 100 = (60000 / 6600) = 600 / 66 = 100/11 % ≈ 9.09% Answer: Principal = Rs 6600; Rate = 9.09 % per annum.
The average age of 10 students is 20. If the teacher’s age is included, the average rises by 2. Find teacher’s age.
The average score obtained by 22 students in a class test is 68 marks. The top place was shared by 3 people who got the same score. If the lowest score ...
The average score of 20 students in a test is 65. Later it is found that the score of one student was wrongly taken as 54 instead of 84. What will be th...
The average of 9 numbers is 100. The average of the first 4 numbers is 65 and the average of the last 4 numbers is 40. What is the 5th number?
Average age of a class of 33 students is 14 years. Average age of the class is increased by 18 months if the age of the teacher is included. Find...
The average number of taxis of three colours (black, white and yellow) in a taxi stand is 155. The number of black taxis is 60 more than that of yellow ...
The average weight of 4 persons is 40 kg. The heaviest person’s weight is 26 kg more than the lightest person’s weight. If the average weight of the...
The average height of each student in a class of 36 students is 169 cm. If 4 new students joined the class, then the average height of the each student ...
Find the mean of the following observations:
45, 54, 42, 56, 46, 48, 52, 50, 57, 43Average marks scored by Vineet in five subjects are 80. The average marks scored by him (excluding his highest and lowest marks) are 72 and lowest marks...
Relevant for Exams:
