# Examples for 9th grade - page 21

- The creek

Workers cleaned the creek within 3 days. The first day cleanse one-fifth the length of the creek, the next day 40% of the length of the stream and the third day 8 km length of the creek. How long is a creek? - Two numbers

We have two numbers. Their sum is 140. One-fifth of the first number is equal to half the second number. Determine those unknown numbers. - 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? - Cube volume

The cube has a surface of 384 cm^{2.}Calculate its volume. - Tank No 8

Tank is filled by one inlet valve with a flow rate of 12 liters per second in 72 minutes. How long take the tank to fill, if we open half an hour after one more inlet? - 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? - 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? - 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? - Thales

Calculate the length of the Thales' circle described to right triangle with hypotenuse 44 cm. - Triangle angles

The angles α, β, γ in triangle ABC are in the ratio 10:5:6. Calculate size of angles. - 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. - Father and son

Father is three times older than his son. 12 years ago father was nine times older than the son. How old are father and son? - Product V2

The price of product was increased by 15%. Price increased by 154. How much money it would cost this product, if it was on the contrary by 23% discounted. - Comparing powers

How many times is number 5^{5}larger than number 4^{5}? - Work

First paver pave pavement for 33 hours. Second for 24 hours. Started first paver and after 5 hours, join the second. How long will they finish pavement? - Product

The product of two consecutive odd numbers is 899. What are this numbers? - Trigonometry

If you know that cos(α) = sin (-968°), what is the angle α? - Event probability

The probability of event G in 9 independent experiments is 0.48. What is the probability that the event G occurs in one experiment (probability is same)? - Rectangle

Area of rectangle is 1430. Its length is 29 larger than the width. What are the dimensions of the rectangle? - Smallest internal angle

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

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