Math practice for 13 year olds - page 116 of 415

Number of problems found: 8285

Rod ratio division
How do you divide a 3 m long rod in a ratio of 1:5? Specify the length of both parts in cm.
Dance couple pairs
Ten girls and seven boys are in the dance group. Only one mixed couple is to go to the competition. How many possible pairs can we choose from?
Skater equipment options
Mike is buying skater equipment. He chooses one of 2 helmets, one of 3 pairs of gloves, one of 4 knee pads, and one of 2 elbow pads. How many different combinations of equipment can he choose?
Car kinetic energy
The car weighs 1850 kg and increases its speed from 27 to 81 km/h. How much has its kinetic energy increased?
Mobile phone settings
Lucia's mobile phone offers a choice of 10 ringtones, seven tones when receiving an SMS, and 15 wallpapers in the background of the display. How many ways can Lucia set up her mobile?
Teacher 3
Teacher Ken is interested in buying a jacket at a discounted price. The price tag says the original price is Php 1250, which is 20% off. What would be his change if he gave the cashier Php 1000?
The price 3
The price of a notebook is 20 percent less than that of a book. By what percent is the book's price higher than the price of the notebook?
Hands coincide
In how many minutes after the second hour do the clock hands coincide?
Steel bar cutting
We must cut three steel bars with 24 dm, 3 m, and 160 cm lengths into equal lengths. Find their maximum length and number.
Hexagon angle size
Determine the size of the ACF angle in the regular ABCDEF hexagon.
Swing balance lever
Two children with different weights sit on the swing, a lever with your shoulders. On the left side sits a child with a capacity of 30 kg, and on the right, a child with a capacity of 20 kg. One swing arm is 150 cm long. How would you seat the children so
Laura bike route
Laura went for a new bike ride. In an hour, her father followed her on the same route at 60 km/h speed and overtook her in 1/2 hour. a) Find the length of Laura's route in kilometers before her father catches up with her. b) Determine in kilometers per ho
Grandmother currant harvest
The grandmother and granddaughter Julia harvest currants in 15 hours of work together. Julia would harvest currants for ten days after 6 hours of work a day. a) Determine in hours how long the harvest would have taken for her grandmother if Julča had not
Calculate radius
The surface of the sphere is 624 cm². Calculate its radius.
Magnifying glass percentage
What magnification of magnifying glass in percent if the magnification is 4x?
PC price increase
The new type of PC became 15% more expensive before Christmas and is now being sold for CZK 13,800, which is 80% of the pre-Christmas (already higher) price. What was the original price of the PC before the price increase?
Cone roof consumption
The roof of a tower has the shape of a lateral surface of a cone with a base diameter of 4.3 m. The angle between the slant side and the base plane is 36°. Calculate the amount of sheet metal needed to cover the roof, allowing 8% for waste.
Spherical layer
What is the volume of the spherical layer that remains after cutting the paragraphs on both sides of the ball, whose height is 3.5 cm? Is the diameter of the ball 24 cm?
Pump power
Determine the pump power if: I pour 3 m³ of water from the tank in 120 seconds with a hose. The height of the hose mouth above the tank is 1.5 m. The water's speed from the hose outlet is 20 m/s.
Fraction and ratios
Fraction and ratios are different names for the same thing.

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