# Examples for 9th grade - page 22

- Plasticine ball

Plasticine balls have radius r_{1}=100 mm, r_{2}=48 cm. For these balls are molded one big ball. Calculate the radius r of the resulting ball. - Machines 2

2 machines for 50 hours produces 2,000 products. How many machines need to buy to make in 30 hours 15,000 products? - Pupils

Four pupils is going via dark hall. Start at one side and have to get to the other side for 17 minutes. They have only one lamp for the trip. The corridor is narrow, they can therefore go up two pupils at a time and go at the slower speed. Each pupil went. - The city 2

Today lives 273000 citizens in city. How many citizens can we expect in 12 years if their annual increase is 2.5%? - Container

First day got off 1/4 water from full container, second day 1/5 of the remaining water. How many percent remain container filled? - Deposit 3

After a year had Martin on bank account € 1764. What was the interest rate when the initial deposit was € 1581? - Alcohol 2

Two types of alcohol one 70% and second 61% give 11 liters of 57% alcohol. How many liters of each type are in the mixture? - Slope

What is the slope of the line defined by the equation -4x -2y = -7 ? - Cube in a sphere

The cube is inscribed in a sphere with volume 6598 cm^{3.}Determine the length of the edges of a cube. - Steps

How many steps you save if you go square estate for diagonal (crosswise), rather than circumvent on the two sides of its perimeter with 298 steps. - Diamond

Determine the side of diamond if its content is S = 500 cm^{2}and one diagonal u_{2}= 46 cm. - Circle arc

Circle segment has a circumference of 13.26 mm and 252.03 mm^{2}area. Calculate the radius of the circle and size of central angle. - Two rooms

Woman cleans the room in 30 minutes a man in 90 minutes. How long will take they clean two rooms? - Apples in baskets

Determine how many apples are in baskets when in the first basket are 4 apples, and in any other is 29 apples more than the previous, and we have eight baskets. - Smallest internal angle

Calculate what size has the smallest internal angle of the triangle if values of angles α:β:γ = 3:4:8 - Disinfecting solution

How much distilled water is necessary to pour into 500 ml of 33% hydrogen peroxide solution to obtain 3% disinfecting solution? - Two looms

On two different looms with different performance can be make required quantity of textile in 6 hours when both work together. On the first machine this quantity of the textile can make in 10 hours. How long should take make same quantity of textile on a s - Probability - tickets

What is the probability that when you have 25 tickets in 5000 that you wins the first (one) prize? - Water reservoir

The water reservoir is filled through one inlet 4 hours later than both together, then another inlet 9 hours later than both together. For how long is filled by each separately? - Piano

If Suzan practicing 10 minutes at Monday; every other day she wants to practice 2 times as much as the previous day, how many hours and minutes will have to practice on Friday?

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