# Examples for 9th grade - page 31

- Four-digit number

Find also a four-digit number, which quadrupled written backwards is the same number. - Water

On the lawn which has area 914 m^{2}rained 3 mm of water. How many liters of water rained? - Trapezoid ABCD

Calculate the perimeter of trapezoid ABCD if we know the side c=15, b=19 which is also a height and side d=20. - Cube 6

Volume of the cube is 216 cm^{3}, calculate its surface area. - Workman - shift

The worker produces 300 components per shift. How many components would be produced in 18 shift, if his performance gradually increased every shift by 3 components? - Tunnels

Mice had built an underground house consisting of chambers and tunnels: • each tunnel leading from the chamber to the chamber (none is blind) • from each chamber lead just three tunnels into three distinct chambers, • from each chamber mice can get to any - The body

The body on the figure consists of cubes with an edge length 10 cm. What surface has this body? - SAS triangle

The triangle has two sides long 7 and 19 and included angle 36°. Calculate area of this triangle. - Katy MO

Kate draw triangle ABC. Middle of AB have mark as X and the center of the side AC as Y. On the side BC wants to find the point Z such that the content area of a 4gon AXZY was greatest. What part of the triangle ABC can maximally occupy 4-gon AXZY? - Mother and daughter

Three years ago mother was three times older than daughter. After nine years she will be only twice old. How old is mother (and daughter)? - Exam average

Average of marks that have on the certificates students of 8.A class in mathematics is exactly 2.45. If we did not add 1 and 3 of sutdents Michael and Alena, who arrived a month ago, it would average exactly 2.5. Determine how many students have class 8. - Warehouse cars

From the warehouse started truck at speed 40km/h. After 1hour 30mins started from the same place same direction a car at speed 70 km/h. For how long and at what distance from the warehouse overtake a truck? - Spirit

From 55% and 80% spirit we would like to produce 0.2 kg of 60% spirit. How many of them we must use in a solution? - Cone container

Rotary cone-shaped container has a volume 1000 cubic cm and a height 12 cm. Calculate how much metal we need for making this package. - Chess

How many ways can select 4 fields on classic chess board with 64 fields, so that fields don't has the same color? - Work

First paver pave pavement for 27 hours. Second for 27 hours. Started first paver and after 4 hours, join the second. How long will they finish pavement? - Gasholder

The gasholder has spherical shape with a diameter 20 m. How many m^{3}can hold in? - Grandfather

The grandfather is three years older than an grandmother. The average age of the grandmother, the grandfather and their seven grandchildren is 28 years. The grandchildren have a total of 105 years. Calculate how old is grandfather. - Bath

In the bath is 30 liters of hot water. Then added 36 liters of cold water at temperature of 19 °C decreased temperature of water to 41 °C. What was the initial temperature of the hot water? - Bronze, tin and copper

Bronze is an alloy of tin and copper. An alloy of 10% tin and 90% copper is Gunmetal. If it contains 20% tin and 80% copper, it is bell metal. How many tons of molten bell metal and how many tons of copper is needed to make 100 tons of Gunmetal?

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