# Examples for 9th grade - page 20

- Variations

Determine the number of items when the count of variations of fourth class without repeating is 50 times larger than the count of variations of third class without repetition. - Vectors

For vector w is true: w = 2u+2v. Determine coordinates of vector w if u=(-8, -5), v=(18, 19) - Cyclist

A cyclist is moving at 26 km/h and follow pedestrian who is walking at speed 7 km/h. Walker has an advantage 13 km. How long take cyclist to catch up with him? - Distance

Calculate distance between two points Z[7; -9] and U[-10; -8]. - Eight palm

There grows 8 palms by the sea. At the first sitting one parrot, on second two, on third sits four parrots on each other twice the previous parrots sitting on a previous palm. How many parrots sitting on eighth palm? - Pupils

Four pupils is going via dark hall. Start at one side and have to get to the other side for 17 minutes. They have only one lamp for the trip. The corridor is narrow, they can therefore go up two pupils at a time and go at the slower speed. Each pupil went. - Water container

Container with water weighs 1.48 kg. When we cast 75% of water container of water weight 0.73 kg. How heavy is an empty container? - Balance

The rod are 1.7 m long hanging weights 2 kg and 12 kg on ends. Where are centre of rod (distance from weight 2 kg) to be in balance? - Students

In the front row sitting three students and in every other row 11 students more than the previous row. Determine how many students are in the room when the room is 9 lines, and determine how many students are in the seventh row. - Two numbers

We have two numbers. Their sum is 140. One-fifth of the first number is equal to half the second number. Determine those unknown numbers. - Book

Alena read a book at speed 15 pages per day. If she read twice as fast she should read a book four days earlier. How many pages have a book? - Angles ratio

In a triangle ABC true relationship c is less than b and b is less than a. Internal angles of the triangle are in the ratio 5:4:9. The size of the internal angle beta is: - Chess

How many different ways can initiate a game of chess (first pass)? - Percentage reduction

Reducing the unknown number by 36% get number 937.3 Determine unknown number. - Kids

How many different ways can sit 5 boys and 5 girls in line, if girls want to sit on the edge? - River

From the observatory 18 m high and 26 m from the river bank, river width appears in the visual angle φ = 14°30'. Calculate width of the river. - Sequence

Write the first 7 members of these sequence: a_{1}= -4 a_{2}= 10 a_{n+2}= a_{n+1}-1 a_{n} - Electronics: Resistors in parallel

From relation for calculating the resistance of parallel combination of resistors: ? Calculate the R, if R_{1}= 8kΩ a R_{2}= 18kΩ - Skiing meeting

On the skiing meeting came four friends from 4 world directions and led the next interview. Charles: "I did not come from the north or from the south." Mojmir "But I came from the south." Joseph: "I came from the north." Zdeno: "I come from the south." W - Collection

John has collected half a bucket of raspberries in 45 minutes, Eva collects the whole bucket in an hour. How many minutes it would take to fill a bucket if the two children work together?

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