Math practice for 13 year olds - page 249 of 428

Number of problems found: 8557

Wave parameters
Calculate the speed of a wave if the frequency is 336 Hz and the wavelength is 10 m.
The painter
For the painter to get the desired color, he must mix green and yellow in a ratio of 4:7. If it has 28 l of green color, how many liters of yellow should he add? How many liters of mixed color does he get?
Triplets From Four Pupils
How many different triplets can be created from 4 pupils if it does not matter the order of the pupils in the triplets?
Diluting Alcohol Solution
I have 35% alcohol and want to make 1 liter of 1% solution. How much ml of alcohol should I put on the bottom of a one-liter container and pour water over it?
Diagonals at right angle
In the trapezoid ABCD, this is given: AB=12cm CD=4cm And diagonals crossed under a right angle. What is the area of this trapezoid ABCD?
Two Inflows Water Volume
Two hundred forty liters of water flow into the tank from 6 tributaries in 6 minutes. The wider one will flow 20 liters more in 9 minutes than the narrower one in 11 minutes. How many liters of water flow out of each inflow in 1 minute?
Hikers Meeting Time Route
A tourist would cover the route from Skalnate Pleso to Hrebienok at a constant speed in 2 hours. His friend would walk the same route from Hrebienk to Skalnaté Pleso in 3 hours. When will they meet if they both go hiking at 9:00?
Cube Volume from Surface
The surface of the cube is 61.44 cm². Calculate its volume.
Verticall growth
The storm broke the vertically growing spruce at 8 meters above the ground. The top fell to the bottom 6 meters from the spruce base. Find the original height of the spruce.
Clock Hands Angle Ten
The hour and minute hands on the clock face make an alpha angle. If you know it's 10 hours and 12 minutes, what is the angle's size?
Construction of the road
Six trucks are supposed to be transported for 18 days to construct the road dam. After three days, the transport company sent two more cars to the construction site. How long will it take to carry the material?
Solve Linear Equation
Solve the equation with the unknown a: 3 (2a + 1) = (a-3) • 4-5
Greg and Bill
Greg is 18 years old. He is six, less than four times Bill's age. How old is Bill?
Sum of dividend
Suppose X is divided separately into 2.63 and 1.40. The results of the individual divisions are added to give a result less than X. What is X?
Peter and Paul
Peter and Paul together have 26 years. Four years ago, Paul was twice older than Peter. How much is Paul and how much is Peter?
Middle number puzzle
In the middle between the unknown number and the number 166 is the number a) 164, b) 200, c) 500 d) 1356 What are the unknown numbers?
Number expression comparison
Which number is 2a-b smaller than a + 2b?
Tree Height Shadow Length
A man 1.65 m tall casts a shadow of 1.25 m. How tall is the tree whose shadow is in debt 2.58 m?
Rod cutting lengths
We want to cut a 90 cm long rod into two parts so that the longer part of the rod is 2 cm shorter than three times the shorter part. Determine the lengths of both parts of the rod.
Tickets
One thousand two hundred sixty tickets sold. On the first day, 80% was sold, and on the second day, it was sold. How many tickets were sold first, and how much the next day?

Do you have unsolved math question and you need help? Ask a question, and we will try to solve it. We solve math question.