Math practice for 13 year olds - page 9 of 428

Number of problems found: 8555

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.
Hands of a clock
At what time between 11 and 12 o'clock will the hands of a clock form an angle of 180°?
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.
A train 3
A train takes 3 hours to go from one station to another station. If its speed is decreased by 12 km/h then the journey time will increase by 45 min. What is the distance between the two stations?
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 square - midpoints
The area of a square ABCD is 36 cm². Find the area of the square obtained by joining the midpoints of the sides of the square ABCD.
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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