Examples for 8th grade - page 5

  1. Drunk man
    drunk-man Drunkman has 2.1‰ of alcohol in the blood. How many grams of alcohol has in blood, if he have 6 kg of blood?
  2. Segments
    abs Which of the pairs of numbers on the number line encloses the longest segment: ?
  3. Tractors
    tractors Fields go plow two tractors with various performance. The first tractor plow whole field in 5 hours, the second tractor plow whole field 5 hours longer. How long take plow whole field with two tractors?
  4. Square diagonal
    square_d Calculate length of the square diagonal if the perimeter is 200 cm.
  5. Pizza master
    pizza_3 Master says that he can splits pizza to 16 parts by five equals straight cuts. Is it possible?
  6. Railways
    railways Railways climb 5.8 ‰. Calculate the height difference between two points on the railway distant 2389 meters.
  7. Seedcake
    pletenky Seedcake costs 50 cents. How many minimum seedcakes we must buy that we can pay in cash only whole euros?
  8. Density - simple example
    mercury Material of density of 1278 kg/m3 occupies a container volume of 80 cm3. What is its mass?
  9. Vinegar 2
    ocet How many percentage of getvinegar solution, if we mix to 14.5 liters of 7.8% and 2.5 liters of 5.8% vinegar?
  10. Road repair
    workers_1 Road repair took 16 days for 34 workers if they worked 6 hours a day. How many days take repair same road 33 workers if they work 6 per day?
  11. Time
    time Write time in minutes rounded to one decimal place: 1 h 42 m 22 s.
  12. Sprayers
    postrekovac The vineyard can be sprayed first sprayer in 5 hours and with the second in 7 hours. How long would it take if we use sprayers both at once?
  13. Monkey
    monkey Monkey fell in 31 m deep well. Every day her scramble 3 meters, at night dropped back by 2 m. On that day it gets hangover from the well?
  14. Team
    football The football team has 11 players. Their average age is 21 years. During the match due to injury, one player withdraws and the average age of the team is 20. How old was injured player?
  15. Discount
    pulover Ladies sweater was twice discounted. First by 17%, then by 17% of the new price. Its final price was 72 USD. Determine the original price of sweater.
  16. Tournament
    turnaj Determine how many ways can be chosen four representatives from 27 students to school tournament.
  17. Exam average
    vysvedcenie_2 Average of marks that have on the certificates students of 8.A class in mathematics is exactly 2.45. If we did not add 1 and 3 of sutdents Michael and Alena, who arrived a month ago, it would average exactly 2.5. Determine how many students have class 8.
  18. Tributaries
    pritok The first tributary fill pool with water in 15 hours. The second tributary fill pool in 10 hours. For how many hours the pool is filled with both tributaries?
  19. Tractors
    tractor 6 tractors started plowing the field that them together take 12 days. Agronomist hesitates to A) after 2 days to withdraw 2 tractors, or B) after 3 days to withdraw 3 tractors. Help him which of these two cases will be plowing done sooner.
  20. Sequence
    arithmetic_seq In the arithmetic sequence is a1=-9, d=4. Which member is equal to the number 147?

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