Examples for 8th grade - page 16
Buses Ikarus and Karosa simultaneously started at 11:00 from the final station. Ikarus is returned to the station after 30 minutes. Karosa after 45 minutes. At what time both buses again returned to the station?
- Train and car
The train and the car started at a constant speed to journey. When the train travels 78 km, the car travels 64 km. How many km travels the train when the car travels 78 km?
Parachutists during freefall firstly held in groups of 4, then of 6, then 9, 12 and finally of 18 members. How many parachutists jump at least should be, if at each group must all be involved.
- Five tractors
Five tractors plow field in 4.8 hours. How long plow this field if after 1.5 hours of work two tractors went to a different field?
Room is 26.2 m long, 23.4 dm wide and 628 cm high. How many people can simultaneously be in this room if for hygiene reasons is calculated 5100 dm3 of air per person?
- Sea water
Mixing 68 kg of sea water with 73 kg rainwater is created water containing 3% salt. How many percent sea water contains salt?
Calculate area of the square with diagonal 70 cm.
- Ladislav in Amsterdam
Ladislav was reward and went to conference in Amsterdam. Conferense fee was € 2184. Calculate how many books Ladislav could buy at the price of 42 and 28 euros if he don't want fill whole home library and he can buy only 63 books?
How many ways can select 3 fields on classic chess board with 64 fields, so that fields don't has the same color?
Calculate the length of the arm r of isosceles triangle ABC, with base |AB| = 16 cm and a height v=10 cm.
- Apples 2
James has 13 apples. It has 30 percent more apples than Sam. How many apples has Sam?
Expression (3a-7).(3a+7) is identical with: ?
What is the reciprocal of the sum of the reciprocals of 7 and 2?
The areas of the two circles are in the ratio 1:15. The larger circle has diameter 25. Calculate the radius of the smaller circle.
I have a box with two hundred pieces of gloves in total, split into ten parcels of twenty pieces, and I sell three parcels. What percent of the total amount I sold?
- Gold coin
Gold coin contains 963 promile pure gold, which is 8.39 g. What is the weight of coin in grams?
John paid 1000 Euros in store for purchase. Calculate value added tax (VAT), which paid in purchase, if the VAT rate is 20%.
- Circumference - a simple
What is the ratio of the circumference of any circle and its diameter? Write the result as a real number rounded to 2 decimal places.
- Pyramid Z8–I–6
Each brick of pyramid contains one number. Whenever possible, the number in each brick is lowest common multiple of two numbers of bricks lying directly above it. That number may be in the lowest brick? Determine all possibilities.
- 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?