Examples for 8th grade - page 5

  1. Invitations
    envelope For every 5 minutes writes Dana 10 invitations, while Anna 14 invitations. How long will write together 120 invitations?
  2. Permill
    permille How many permill is 1931 from 166456?
  3. Compare II
    powers Which of the numbers 158, 815 is greater?
  4. Tunnels
    Mysky Mice had built an underground house consisting of chambers and tunnels: • each tunnel leading from the chamber to the chamber (none is blind) • from each chamber lead just three tunnels into three distinct chambers, • from each chamber mice can get to any
  5. Area codes
    us_codes How many 6 digit area codes are possible if the first number can't be zero?
  6. Madams
    womans During the spring cleaning ladies going to wash windows. Mother takes wash all the windows 5 hours, the grandmother 3 times longer and Paula wash all windows in 5 hours. How many hours will spend washing the windows this "women's team" if working togethe
  7. ABS
    sphere_nice What is the value of ? ?
  8. 2nd class variations
    cards From how many elements you can create 6480 variations of the second class?
  9. Radius
    green_circle Determine the radius of the circle, if its perimeter and area is the same number.
  10. Circle chord
    circleChord What is the length d of the chord circle of diameter 58 mm, if distance from the center circle is 24 mm?
  11. Garden
    garden_2 Father dig up the garden in 13 hours. Son in 18 hours. How many hours take dig up the garden together?
  12. Excavation
    vykop_ryha Mr. Radoslav calculated that excavation for a water connection dig for 10 days. His friend would take 7 days. Radoslav worked 3 days alone. Then his friend came to help and started on the other end. On what day since the beginning of excavation they met?
  13. Number
    percent What number is 24 % smaller than the number 51?
  14. Powers
    math_fun Is true for any number a,b,c,d equality:? ?
  15. Present
    prezent Gift box has rectangular shape with dimensions of 3×3×5 cm. Martin wants to cover with square paper with sides of 10 cm. How much paper left him?
  16. River
    kongo_river Calculate how many promiles river Hudson average falls, if on section long 921 km flowing water from 1224 m AMSL to 154 m AMSL.
  17. Gauss
    kfgauss Help little C.F. Gauss sum all the integers from 1 to 340.
  18. Katy MO
    reporter_saved6 Kate draw triangle ABC. Middle of AB have mark as X and the center of the side AC as Y. On the side BC wants to find the point Z such that the content area of a 4gon AXZY was greatest. What part of the triangle ABC can maximally occupy 4-gon AXZY?
  19. Two workers
    Frog Two workers together execute some work in 10 days. The first worker would have done himself in 20 days. How many days would have done himself a second worker?
  20. Accidents
    nehoda-pomnik The count of accidents in 1993 caused 8009 women which is 7.1%. How many men caused the accidents?

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