# Examples for secondary school students - page 24

1. Field with vegetables Field planted with vegetables has shape of a rectangular isosceles triangle with leg length of 24 m. At the vertices of the triangle are positioned rotating sprinklers with a range of 12 m. How much of the field sprinkler doesn't irrigated?
2. Swing A child weighing 12 kg is sitting on a swing at a distance of 130 cm from the axis of rotation. How far away from the axis of rotation (center) must sit down his mother weighs 57 kg if she wants to be swing in balance?
3. Half life Determine the half life of bismuth, when bismuth weight from the original weight of 32 g was only 2 grams in 242 minutes.
4. The body The body on the figure consists of cubes with an edge length 10 cm. What surface has this body?
5. Rhombus The rhombus with area 68 has one diagonal is longer by 6 than second one. Calculate the length of the diagonals and rhombus sides.
6. Water On the lawn which has area 914 m2 rained 3 mm of water. How many liters of water rained?
7. Number Is number 5.146852 irrational?
8. Tickets Tickets to the zoo cost \$4 for children, \$5 for teenagers and \$6 for adults. In the high season, 1200 people come to the zoo every day. On a certain day, the total revenue at the zoo was \$5300. For every 3 teenagers, 8 children went to the zoo. How many te
9. 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?
10. SAS triangle The triangle has two sides long 7 and 19 and included angle 36°. Calculate area of this triangle.
11. 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)?
12. Diagonals in diamond In the rhombus is given a = 160 cm, alpha = 60 degrees. Calculate the length of the diagonals. Calculate how many g's (gravity accelerations) feel glider pilot when turning the horizontal circles of radius 148 m flying at 95 km/h. Centripetal acceleration is proportional to the square of the speed and inversely proportional to the radius of rotation
14. 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?
15. Chess How many ways can select 4 fields on classic chess board with 64 fields, so that fields don't has the same color?
16. 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.
17. 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.
18. 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?
19. Gasholder The gasholder has spherical shape with a diameter 20 m. How many m3 can hold in?
20. Elections In elections candidate 10 political parties. Calculate how many possible ways can the elections finish, if any two parties will not get the same number of votes.

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