1. A car owner buys diesel at Rs.7.50, Rs. 8 and Rs. 8.50 per litre for three successive years. What approximately is the average cost per litre of diesel if he spends Rs. 4000 each year?
1. Rs. 8
2. Rs. 7.98
3. Rs. 6.2
4. Rs. 8.1
Answer & Explanation Answer:- 2 Explanation :- Total amount spent = Rs. (3 x 4000) = Rs. 12000. 2. A family consists of two grandparents, two parents and three grandchildren. The average age of the grandparents is 67 years, that of the parents is 35 years and that of the grandchildren is 6 years. The average age of the family is Answer:- 2 Explanation :- Total age of the grandparents = 67 × 2 = 3. The average weight of 16 boys in a class is 50.25 kg and that of the remaining 8 boys is 45.15 kg. Find the average weights of all the boys in the class. Answer & Explanation Answer:- 1 Explanation :- Average = [(16*50.25) + (8* 45.15)] /(16 + 8) 4. A library has an average of 510 visitors on Sundays and 240 on other days. What is the average number of visitors per day in a month of 30 days beginning with a Sunday? Answer & Explanation Answer:- 3 Explanation :- A month Starting with sunday has 5 sundays therefore other days = 30 – 5 = 25 5. A student’s mark was wrongly entered as 83 instead of 63. Due to that the average marks for the class got increased by 1/2. What is the number of students in the class? Answer & Explanation Answer:- 2 Explanation :- Let the total students in the class = x
Total quantity of petrol = (4000/7.50) + (4000/8) + (4000/8.50) = 4000[(2/15) + (1/8) + (2/17)] = (76700/51)
Average cost = (12000/(76700/51) ) = (12000*51)/76700 = 7.98
1. 32 2/7 years
2. 31 5/ 7 years
3. 28 1/7 years
4. 30 5/7 years
Total age of the parents = 35 × 2
Total age of the grandchildren = 6 × 3
Average = [ ( 67 × 2 ) + ( 35 × 2 ) + ( 6 × 3 ) ] / 7 = 31 and 5/7
1. 48.55
2. 42.25
3. 50
4. 51.25
Average = (804 + 361.20)/24 = 48.55
1. 290
2. 304
3. 285
4. 270
Visitors on 5 sundays = 5 * 510
Visitors on other 25 sundays = 210 *25
[(510 × 5) + (240 × 25)] / 30 = 8550/30 = 285
1. 45
2. 40
3. 35
4. 30
Increase in the marks = 83 – 63 = 20
20/x = 1/2
x = 40