# Examples for 8th grade - page 2

- Playing cards

How many possible ways are to shuffle 7 playing cards? - Shelf

How many ways are there to arrange 9 books on a shelf? - Logic

A man drinks a barrel of water for 31 days, woman for 58 days, for how many days they drink barrel together? - Ace

From complete sets of playing cards (32 cards) we pulled out one card. What is the probability of pulling the ace? - Series

Andrew wrote this series of numbers: 1,3,7,15, .... n. Which number in the series does not belong? ? - Percent calculation

Calculate 22% if 68% is 42. - Trapezoid

Are diagonals in a rectangular trapezoid perpendicular and bisect the angles? - Road

Between cities A and B is route 3 km long of rise average 4‰. Calculate the height difference of cities A and B. - KLMN

In the trapezoid KLMN is given this informations: 1. segments KL and MN are parallel 2. segments KL and KM has same length 3. segments KN, NM and ML has same length. Determine the size of the angle KMN. - Painter Pavel

Painter Pavel painted the fence for 20 hours and painter Petr the same fence painted for 17 h. How long should take painted the fence together? - Right Δ

Right triangle has length of one leg 7 cm and length of the hypotenuse 25 cm. Calculate the height of the triangle. - Cylinder - h

Cylinder volume is 242 cm^{3.}Base radius is 1 cm. Calculate the height of the cylinder. - Center traverse

It is true that the middle traverse bisects the triangle? - Christmas Day

In leap years was 53 Sundays. On what day of the week fell to Christmas Day? - Workers

Two workers fulfill a certain task when working together for 7 days, the first if he worked himself done work in 18 days. How many days will do whole job a second worker? - AVG of INT

What is the average of the integers from 7 throuht 15 inclusive? - Coin and die

Flip a coin and then roll a six-sided die. How many possible combinations are there? - Diofant 2

Is equation ? solvable on the set of integers Z? - Beer

After three 10° beers consumed in a short time there are 7.4 g of alcohol in 5 kg adult human blood. How much is it per mille? - MO SK/CZ Z9–I–3

John had the ball that rolled into the pool and it swam in the water. Its highest point was 2 cm above the surface. Diameter of circle that marked the water level on the surface of the ball was 8 cm. Determine the diameter of John ball.

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