Math practice for 13 year olds - page 7 of 434
Number of problems found: 8665
- A circular track
The inner circumference of a circular track is 220 m, and the width of the track is 7 m. Calculate the cost of putting up a fence along the outer circle at the rate of 50 USD/m. - Temperature bellow zero
At 3 PM, the temperature was 12 F. It then began dropping 2 F every hour for 7 hours. What was the temperature after 7 hours? - Average age 4
The average age of 31 people in a group is 19. If one person is reduced to 18, the average age becomes 18. Find the age of the reducing person. - One-third 18
One-third of a certain journey was covered at the speed of 20 km/h, one-fourth at 30 km/h, and the rest at the speed of 50 km/h. Find the average speed of the whole journey. - Play with mean
The sum of few numbers is 450 and their mean is 50 and if another number 100 is included, the mean would be? - Interior angles 4
How many degrees are in the sum of the interior angles of a quadrilateral? - Big cities
City A has a population of 136000 which is decreasing at the rate of 2400/yr. City B has a population of 84000 which is increasing at the rate of 1600/yr.In how years will the population of two cities become equal?
- Milk bottles
A container of milk was 4/5 full. When 12 bottles of milk were taken out and 8 bottles of milk poured into it, it was 3/4 full.How many bottles of milk can the container contain? - Full-tank
A full-tank of petrol a car lasts for 10 days. If driver starts using 25% more everyday, how many days will the full-tank petrol last? - A recycling
A recycling bin contained 40 pounds of plastic in October and 50 pounds of plastic in November. By what percentage did the amount of plastic increase from October to November? - Automobil
The car traveled three quarters of the total journey at a speed of 90 km/h and the remaining part of the journey at a speed of 50 km/h. Find its average speed. - The world record
The world record for the longest dogtail is 77/100 meters. The previous record was 1/20 meter shorter than the current record. Was the previous record holder longer than 3/4 meter? - 15 years 15 years hence, a man will be just 4 times as old as he was 15 years ago. Find his present age.
- The dimensions
The dimensions of a rectangular piece of paper are 22 cm × 14 cm. It is rolled once across the breadth and once across the length to form right circular cylinders of biggest possible surface area. Find the difference in volumes of the two cylinders that w - Consecutive odd nums
Sum of four consecutive odd numbers is 40. Find the numbers.
- Time and distance
A man walking at a speed of 4 km/h can reach a destination in 3 hours. If he increases his speed by 1 km/h, how much time will he save? - Spheres to cone
Two solid spheres of radii 2 cm and 4 cm are melted and recast into a cone of height 8 cm. Find the radius of the cone so formed. - The remainder
Find the remainder if 17²00 is divided by 18. - A contractor 2 A contractor has to complete his contract in 92 days. 234 men were set to do the work, each of them works for 16 hours/day. After 66 days, 4/7 of the work is completed. How many additional men may be employed, so that the work may be completed in time, ea
- The average 16
The average of 50 numbers is 38. If the two numbers 45 and 55 are not considered, what will be the average of remaining numbers?
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