Math practice for 13 year olds - page 304 of 434
Number of problems found: 8665
- Cross section
The cross-section ABCD of a swimming pool is a trapezium. Its width is AB=14 meters, the depth at the shallow end is 1.5 meters, and at the deep end is 8 meters. Find the area of the cross-section. - Cube wall
Calculate the cube's diagonal if you know that one wall's surface equals 36 centimeters square. Please also calculate its volume. - Cube surface area
The cube's surface was originally 216 centimeters square. It has shrunk from 216 to 54 centimeters square. Calculate the percent change in the edge of the cube. - Mow the lawn
Dano would mow the lawn in 12 hours and Milada in 16 hours. How long will it take the lawn mow together? - Lines
How many lines can be drawn with 8 points if three points lie on one line and the other any three points do not lie on the same line? - Three-digit
How many three-digit natural numbers do not have the number 7? - Intersect 5216 At how many points do ten lines intersect if no two are parallel?
- Book read
If Petra read ten pages per day, she would read the book two days earlier than she read six pages a day. How many pages does a book have? - Ratio of two unknown numbers
Two numbers are hidden. Their sum is 30. We calculate one-sixth of a larger number and add it to both numbers. So we get new numbers whose ratio is 5:7. Which two numbers are they? - Mason with assistant
Mason had to complete the work in 10 days. Two and a half days later, his assistant arrived. Together, they completed the work in the next three and a half days. How many days would he need an assistant for the same work? - Direct route
From two different places A and B, connected by a direct route, Adam (from city A) and Bohus (from city B) started at a constant speed. As Adam continued to go from A to B, Bohus turned around at the time of their meeting, and at the same speed, he return - Fulfillment 5210
This company can complete the order in 168 days. The second company is better equipped and can fulfill the order in 120 days. The companies will fulfill the orders together. Determine how long it will take them to fulfill the order and in what proportion - Cars speeds
The distance from city A to city B is 108 km. Two cars were simultaneously started from both places. The speed of a car coming from city A was 2 km/h higher than the second car. What was the speed of each car if they met in 54 minutes? - Odd numbers
The sum of four consecutive odd numbers is 1048. Find those numbers. - Two numbers
The sum of the two numbers is 1. Find both numbers if you know that half of the first equals one-seventh of the second number.
- Testing
Students in high school have 10 points for each good-solved task. Five points deduct the wrong answer. After solving 20 tasks, student Michael had 80 points. How many tasks did he solve correctly, and how many were wrong? - Cars 6
At 9:00 AM, two cars started from the same town and traveled at a rate of 35 miles per hour, and the other car traveled at a speed of 40 miles per hour. After how many hours will the cars be 30 miles apart? - Boys and girls 2
The ratio of boys to girls in the math club is 4:3 . After eight more girls join the club, the ratio becomes 1:1. How many members are there in the club now? - Pipe cross section
The pipe has an outside diameter of 1100 mm, and the pipe wall is 100 mm thick. Calculate the cross-section of this pipe. - Unknown number 24
If we add 20, we get 50% of its triple. What is this unknown number?
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