# Examples for 8th grade - page 34

- Efficiency

What is the power output of kettle 2 kW with efficiency 90%? - Rectangle

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

Andrew, Lenka and Rasto have together 232 pears. Lenka has 28 more than Rasto and Rasto pears have 96 more than Andrew. Determine how much each of them has pears. - Solution

What amount of 80% solution and what amount of water is needed to mix in order to obtain two liters of 60% solution of this mixture? - Three siblings

Three siblings have birthday in one day-today. Together they have 35 years today. The youngest is three years younger than middle and the oldest is 5 years older than middle. How old is each? - Brackets

Place one pair of brackets in expression 20-16 + 10 - 4 - 2 so that the result will be 0. - Water lake

The length of the lake water is 8 meters width 7 meters and depth 120 centimeters. How many liters of water can fit into the water lake? - Sisters

Sisters Janka and Danka are saved together 220 CZK. On a trip to Janka wants to take a fifth of her savings and Danka quarter. Then they will have 50 CZK on the trip. How much money saved Janka and Danka? - Mukls

The working group, in which 6 workers would ordered job completed within 21 working days. How many workers must be accept yet that the contract will be completed in 14 working days? - Plan scale

At what scale is drawn plan of the building, where one side of the building is 45 meters long is on the plan expressed by a straight line 12 mm long. - 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? - Unknown integer

Find the smallest integer that: divided by 2, the remainder is 1 divided by 3 the remainder is 2, divided by 4 remainder is 3, ... divided by eight reminder is 7, by 9 reminder is 8. - The professor's birthday

Professor of mathematics had 36 birthdays. The director congratulated him. The professor asked the director: "And how old are you?" The director replied: "I'm exactly twice as many years than you were when I was old as to you today." How old is the direc - Flowerbed

On the flowerbed was planted 310 flowers - pansies and crayons. During the first week wilts quarter of pansies and an eighth crayons, which is 20% of all flowers. How many pansies were planted on the flowerbed? - Addends

Number 389 divide into the two addends that the first was 6 greater than 60% of the second. Determine these addends. - Equilateral triangle

How long should be the minimum radius of the circular plate to be cut equilateral triangle with side 7 mm from it? - ŽSR

Calculate fixed annual personnel costs of operating monorail line 106 km long if every 5 km is station, which serve three people - one dispatcher and two switchman in 3-shift operation. Consider the average salary of the employee 847 €. - Weightlifter

Weightlifter lifted 75% of its weight. Determine how much weight lifted when he weighs 132 kg. - Football match 4

In a football match with the Italy lost 3 goals with Germans. Totally fell 5 goals in the match. Determine the number of goals of Italy and Germany. - Loading car

The car was loaded with 78 boxes weighing 19 kg. How many 25kg boxes can load if the total weight is the same?

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