# Examples for 7th grade (seventh) - page 81

1. Metal tube Calculate the metal tube mass 8dm long with the outer radius 5cm and the inner radius 4.5cm and 1cm3 of this metal is 9.5g.
2. Natural gas in kWh Gas consumption for 2017 was 11,301 kWh I paid 532 € How much 1 m3?
3. Grandfather and grandmother The old mother is 5 years younger than the old father. Together they are 153 years old. How many years has each of them?
4. Temperature 5 Temperature outside starts at 0 Fahrenheit. Over time the temperature changes at a rate of -0.6 Fahrenheit per hour. How long will it take for the temperature to reach -4.5 Fahrenheit?
5. Two trains There were 159 freight wagons on the railway station creating 2 trains. One had 15 more wagons than the other. How many wagons did each train have?
6. Paper box Calculate whether 11 dm² of paper is sufficient for gluing a box without a lid with bottom dimensions of 2 dm and 15 cm and 12 cm high. Write result as: 0 = No, 1 = Yes
7. Complementary angles 2 Two complementary angles are (x+4) and (2x - 7) find the value of x
8. Water tank What is the height of the cuboid-shaped tank with the bottom dimensions of 80 cm and 50 cm if the 480 liters of water reaches 10 cm below the top?
9. Iron pole The iron pole is in the ground 2/5 of its length, partly above the ground 1/3 is yellow, and the unpainted section is 6 m long. How long is the entire column?
10. A pipe A radius of a cylindrical pipe is 2 ft. If the pipe is 17 ft long, what is its volume?
11. Tilapia A fish vendor sells 5/7 kilos of tilapia for 73.50. If you will buy 2 1/7 kilos of tilapia, how much will it cost?
12. Playing How long have we trained on the pitch when we know that the warm-up took 10 minutes, we trained passes for one-third of the time and we played football half the time?
13. Dance group The dance group formed groups of 4, 5, and 6 members. Always one dancer remains. How many dancers were there in the whole group?
14. Equation 29 Solve next equation: 2 ( 2x + 3 ) = 8 ( 1 - x) -5 ( x -2 )
15. Area of rectangle How many times will increase the area of the rectangle, if we increase twice the length and at the same time we decrease the width by the half?
16. Tickets On Monday, 33 tickets were sold. Every next day, twice as many as the previous day. How many tickets were sold on Friday and how many totally from Monday to Friday?
17. Isosceles triangle The circumference of the isosceles triangle is 32.5 dm. Base length is 153 cm. How long is the leg of this triangle?
18. Dort The cube-shaped cube box has the dimensions of 30 cm × 30 cm × 12 cm. How many CZK (Czech crowns) would cost be the biggest cake that would fit into the box when a 10 cm³ cake costs CZK 0.5? The cake has the same shape as the box.
19. Temperature increase If the temperature at 9:am is 50 degrees. What is the temperature at 5:00pm if the temperature increases 4 degrees Fahrenheit each hour?
20. Glass with icecream We have 6 kinds of ice cream and 5 kinds of fruit. We put 3 cups of ice cream and 2 fruits into each glass. How many can unique decorated glasses be?

Do you have an interesting mathematical word problem that you can't solve it? Enter it, and we can try to solve it.

To this e-mail address, we will reply solution; solved examples are also published here. Please enter the e-mail correctly and check whether you don't have a full mailbox.

Please do not submit problems from current active competitions such as Mathematical Olympiad, correspondence seminars etc...