# Examples for 8th grade - page 91

- UN 1

If we add to an unknown number his quarter, we get 210. Identify unknown number. - Two boats

The sightseeing boat sail at 25 km / h. The cruise take 6 hours. How long the another boat sails at 60 km/h? - Trees

Along the road were planted 250 trees of two types. Cherry for 60 CZK apiece and apple 50 CZK apiece. The entire plantation cost 12,800 CZK. How many was cherries and apples? - Pumping

The tank is filled with a larger pump in 12 hours and with scond pump in 15 hours. For how long does the tank fill when both pumps are switched on at the same time? - Conical area

A right angled triangle has sides a=12 and b=19 in right angle. The hypotenuse is c. If the triangle rotates on the c side as axis, find the volume and surface area of conical area created by this rotation. - Equilateral triangle ABC

In the equilateral triangle ABC, K is the center of the AB side, the L point lies on one-third of the BC side near the point C, and the point M lies in the one-third of the side of the AC side closer to the point A. Find what part of the ABC triangle conta - Three granaries

Three granaries hold 7,800 metric cent (q) of grain. In the first, 70 tonnes of grain was more than the second and in the third it was 120 tonnes less than in the second. How many grain were in each granary? - Two lands

The common area of the two neighboring lands is 964 m^{2}. The second land is 77 m^{2}smaller than twice the size of the first land. Find the areas of each land. - Diver and pressure

Determine what pressures is exposed diver without a suit at a depth of 15 meters, with a small space suit at a depth of 25 meters and a massive suit at a depth of 70 m in water. - Years

Susan is 3 years and as she will be old as Teodor now him will be 11. How old is Teodor today? - Drying apples

By drying, apples lose 85% of their weight. How many kgs of dried apples do we get from 820 kilograms of fresh? - Ladder

The ladder has a length 3.5 meters. He is leaning against the wall so that his bottom end is 2 meters away from the wall. Determine the height of the ladder. - Weightlifter

Weightlifter lifted 75% of its weight. Determine how much weight lifted when he weighs 132 kg. - Forces on earth directions

A force of 60 N [North] and 80 N [East] is exerted on an object wigth 10 kg. What is the acceleration of the object? - Hexagon area

The center of the regular hexagon is 21 cm away from its side. Calculate the hexagon side and its area. - Chord

It is given to a circle k(r=6 cm) and the points A, B such that / AB / = 8 cm lies on k. Calculate the distance of the center of circle S to the midpoint C of the segment AB. - Cancer

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

The gardener bought trees for 960 CZK. If every tree was cheaper by 12 CZK, he would have gotten four more trees for the same money. How many trees did he buy? - Shots

Determine the percentage rate of keeper interventions if from 32 shots doesn't caught four shots. - Walkers

Walker, which makes 120 steps per minute, make distance from point A to point B for 55 minutes. The length of his step is 75cm. For how long does this distance go boy who will do 110 steps 60 cm long in a minute?

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