# Examples for 8th grade - page 41

- Two boxes-cubes

Two boxes cube with edges a=38 cm and b = 81 cm is to be replaced by one cube-shaped box (same overall volume). How long will be its edge? - Three numbers

The sum of the three numbers is 287. These numbers are in a ratio of 3: 7: 1/4 Define these numbers - Cylinder

The cylinder surface is 859 dm^{2}, its height is equal to the radius of the base. Calculate height of this cylinder. - Medal

Calculate the approximate weight of the gold Olympics medal, if its diameter is 8 cm and a thickness 6 mm. The density of gold find out in the tables or on the Internet. - Parallelogram +ľ

| AB | = 76cm, | BC | = 44cm, angle BAD = 30 °. Find the area of the parallelogram. - Nuts, girl and boys

Milena collected fallen nuts and called a bunch of boys let them share. She took a condition: the first boy takes one nut and tenth of the rest, the second takes 2 nuts and tenth new rest, the third takes 3 nuts and tenth new rest and so on. Thus managed. - Daughters

The man conducting the census asks a woman to age of three daughters. Woman says when multiply the age getnumber 72; if their ages add up, get a number of our house, as you see. The man says: That is not enough to calculate their ages. She says: my oldes - Equator

Suppose that tourist went on foot over the Globe equator. How many meters more track made his hat on his head as the shoes on your feet? The radius of the earth is 6378 km and height of the tourist is 1.7 m. - Motion 2

At 10 o'clock started from place A car speed at 90 km/h. 20 minutes after started from the place B at speed 60 km/h another car. Distance places A and B is 120 kilometers. What time and where they meet? - Acute angles

Sizes of acute angles in the right-angled triangle are in the ratio 1: 3. What is size of the larger of them? - Freight and passenger car

The truck starts at 8 pm at 30 km/h. Passenger car starts at 8 pm at 40 km/h. Passenger arrives in the destination city 1 hour and 45 min earlier. What is the distance between the city of departure and destination city? - Digging companies

Company A would dig a pit for 12 days, company B for 15 days, company C for 20 days and the company D for 24 days. Work began together companies C and D, but after three days joined them other two companies. How long took to dig a pit? - Square Number

If to a square of integer number add 31, we get the square of next integer number. What is the original number? - Bicycles

You're the owner of the transport 's learning playground. Buy bicycles of two colors but you've got to spend accurately 120000 Kč. Blue bike costs 3600Kč and red bicycle 3200Kč. - Arc

What area of a circle occupied the flowers planted in the arc of a circle with radius 4 m with central angle 45°? - For thinkings

The glass cube dive into the aquarium, which has a length of 25 cm, width 20 cm and height of 30 cm. Aquarium water rises by 2 cm. a) What is the volume of a cube? b) How many centimeters measure its edge? - Round table

Round table with diameter d = 105 cm is coated by square tablecloth with a side length 121 cm. About how many cm is higher center of tablecloth than its cornes? - Concentric circles

In the circle with diameter 19 cm is constructed chord 9 cm long. Calculate the radius of a concentric circle that touches this chord. - Mr Novak

Mr Novak earns an average 1249 euros. When increasing the salary they gave him a choice: ? What is better choice for Mr Novak? - Nuts

How many we must have at least nuts if we can equally divide it to 10 children, 11 children or 19 children and any nut left?

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