# Examples for 8th grade

- Cuboid enlargement

By how many percent increases the volume of cuboid if its every dimension increases by 30%? - Content area and percents

Determine what percentage is smaller cube surface, when the surface area of the wall decreases by 25%. - Glass

How many glass are needed to produce glass with base regular 5-gon if one base triangle in the base is 4.2 square cm and the height is 10 cm? - Average speed

What is the average speed you have to move the way around the world in 80 days? (Path along the equator, round to km/h). - Unknown number 7

16% of the unknown number is by 21 less than unknown number itself. Determine the natural unknown number. - Three children

3 children eat 8 chocolates in 6 days. How many chocolates 6 children eat in 18 days? - Tunnels

Mice had built an underground house consisting of chambers and tunnels: • each tunnel leading from the chamber to the chamber (none is blind) • from each chamber lead just three tunnels into three distinct chambers, • from each chamber mice can get to an - Three friends

Three friends divided the profit 104,650 CZK, so that for every 4 CZK, which got the first friend equals 5 crowns for second and for every 9 CZK, which got the second equals 16 CZK for third. Question: Who got the most and how much. - Z9-I-4

Kate thought a five-digit integer. She wrote the sum of this number and its half at the first line to the workbook. On the second line wrote a total of this number and its one fifth. On the third row she wrote a sum of this number and its one nines. F - Runner 2

Marian run 12 meters in 8 seconds. How far would Marian run for 70 seconds, if still run at the same pace? - Pet store

In a pet store, they are selling out the fish from one aquarium. Ondra wanted half of all fish, but they don't wish cut by hal fany fish he got one more than demanded. Matthew wished the remaining half of the fish, but as Andrew got half the fish more t - Cancer

Of the 80 people 50 people ill cancer. What percentage of people isn't ill? - Money duo

Julius and Mark have together 45 euros. Mark has 50% more money than Julius. Determine the amount of money that have Mark and Julius. - Exponential equation

Determine the value of having y in the expression (3^y): (4^-1)=36. Unknown y is a natural number greater than zero. - Raspberries

Dano had 20 raspberries. John had 90% more raspberries than Dano. Determine how many raspberries have Dano and Juraj together. - Rectangle

Perimeter of rectangle is 48 cm. Calculate its dimensions if they are in the ratio 5:3 (width:height) - Linear system

Solve this linear system (two linear equations with two unknowns): x+y =36 19x+22y=720 - Sales off

shoes cost x euros. First they are discounted by 50%, and then 25% of the new amount. Determine what percentage of the total cost is cheaper. - Price saleoff

Shoes standing y euros. At first they were discounted by 12% and then 50% of the new amount. After this double cheapening the cost was exactly 22 euros. Determine the original price of shoes. - Equation

Solve the equation: 1/2-2/8 = 1/10; Write the result as a decimal number.

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