# Examples for 9th grade

- Train speed

Two guns were fired from the same place at an interval of 10 minutes and 30 seconds, but a person in a train approaching the place hears second shot 10 minutes after the first. The speed of the train (in km/hr), supposing that sound travels at 340 m/s is: - Two melons

There are 2 melons in the box. Together they weigh 11kg. The weight of green is 3 kg less than three times the weight of yellow. What is the weight of a green melon? - Average age

The company of five people has an average age of 46 years. The average age of the first four is 43 years. How many years has the fifth member of this company? - Rain

It rains at night. On 1 m^{2}of lake will drop 60 liters of water. How many cm will the lake level rise? - 12 apples

12 apples and 2 loaves of bread cost 5.76 and 6 apples and 3 loaves of bread cost 7.68. How much is a loaf of bread? - Father 7

Father is 6 times older than his son. After 4 years, the father will only be 4 times older. What are their present ages? - Equilateral triangle

Calculate the area of an equilateral triangle with circumference 72cm. - A candle

A candle shop sells scented candles for $16 each and unscented candles for $10 each. The shop sells 28 candles today and makes $400. a. Write a system of linear equations that represents the situation. b. Solve the system to answer the questions: How - A residential

A residential colony has a population of 5400 and 60 litres of water is required per person per day. For the effective utilization of rain water, they constructed a water reservoir measuring 48m × 27m × 25m to collect the rain water. For how many days, th - Surface of cubes

Peter molded a cuboid 2 cm, 4cm, 9cm of plasticine. Then the plasticine split into two parts in a ratio 1:8. From each part made a cube. In what ratio are the surfaces of these cubes? - The bulbs

The bulbs are connected serially two bulbs and one resistor. Each bulb has a resistivity of 100 ohms and resistor of 60 ohms The voltage source in the circuit is 24 volts. Do you know what voltage to measure on individual appliances? - Diagonal to area

Calculate the area of a rectangle in which the length of the diagonal is 10 cm. - Sixty

Sixty percent of one-fifteen of the total is equal to thirty. What are two percent of the total? - Flying

The airplane from Prague to Bratislava was flying at a speed of 60 km/h less and back by 70 km/h greater than the original speed. What was the original speed if the plane returned to Prague according to the timetable? - 13 tickets

A short and long sightseeing tour is possible at the castle. Ticket for a short sightseeing circuit costs CZK 60, for a long touring circuit costs CZK 100. So far, 13 tickets have been sold for 1140 CZK. How much did you pay for tickets for a short tour? - Girls

The children's competition was attended by 63 girls, which is 30% of all children's participants. How many children attended this competition? - Perimeter of a rectangle

If the perimeter of a rectangle is 114 meters and the length is twice the width plus 6 meters, what are the length and width? - Percentage 10

52 shorts and missed 13. Calculate percentage - Test points

If you earned 80% of the possible 40 points, how many points did you miss to get 100%? - Commission

Daniel works at a nearby electronics store. He makes a commission of 15%, percent on everything he sells. If he sells a laptop for 293.00$ how much money does Daniel make in commission?

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