# Time + prime numbers - problems

1. Racing track
On the racing track circling three cars. The first passes one circuit for 8 seconds, the second for 20 seconds and a third for 8 seconds. a) Calculate number of seconds since the start to catch all three cars together for the first time again across the s
Grandson with grandpa they counted how many years have together. Their product is 365. How many years is the sum of their years.
3. Buses 4
intervals: 1st bus 40 min. 2nd bus 2h 3rd bud 20min How long take them to meet - as soon as possible?
4. Two months
Mars has two months, Phobos and Deimos. Phobos orbits around Mars in 7 hours 39 minutes and Deimos in 30 h 14 min. How long will repeat the relative position of the three celestial bodies?
5. Digits of age
The product of the digits of Andrew age as 6 years ago and not equal to 0. Andrew age is also the smallest possible age with this two conditions. After how many years will be the product of the digits of Andrew age again the same as today?
6. Tram stop
At the tram stop met tram No. 4 and no. 5 at 10 AM. Tram no. 4 runs every 5 minutes, tram No. 5 at an interval of 7 minutes. How many times will meet until 12 o'clock?
7. Buses
At the bus stop is at 10 o'clock met buses No. 2 and No. 9. Bus number 2 runs at an interval of 4 minutes and the bus number 9 at intervals of 9 minutes. How many times the bus meet to 18:00 local time?
8. Two friends
Two friends met as a good man perish together for a beer. After recovery the most important topics (politics, women, football ...), one asks: - And how many do you have children? - I have 3 children. - And how many years have? Friend already not want to an
9. Runners circle
Pepa circles the track in 36 seconds. Kamil in 42 seconds. They started together. How many seconds will meet again at the start?
10. Trams 2
Square passes two lines of tram. One running every nine minutes, a second interval of 15 minutes. Exactly at 12 o'clock arrived two tram lines in the square. How soon should a similar situation arise again?
11. Ships
Red ship begins its circuit every 30 minutes. Blue boat begins its circuit every 45 minutes. Both ships begin their sightseeing circuit in the same place at the same time always at 10:00 o'clock. a / What time does meet boat again? b / How many times a da
12. Bus lines
Buses connections are started from bus stop on its regular circuit as follows: No. 27 bus every 27 minutes and No.18 every half hour. What time started this two bus lines run if the bus stop met at 10:15 am.?
13. Trams
Two trams started at the same time from the same place. One tram journey takes 30 minutes and the second 45 minutes to its final stop. How long will trams meet again?
14. Two buses
The first bus runs 15 minutes the second bus runs after 21 minutes. Together they both leave at 7:00 on Monday. When and what day will they meet?
15. Year 2018
The product of the three positive numbers is 2018. What are the numbers?
16. Clock's gears
In the clock machine, three gears fit together. The largest has 168 teeth, the middle 90 teeth, and the smallest 48 teeth. The middle wheel turns around its axis in 90 seconds. How many times during the day do all the gears meet in the starting position?
17. Hectares
The tractor plows the first day of 4.5ha, the second day 6.3ha and the third day 5.4ha. It worked whole hours a day, and its hourly performance did not change and was the highest of the possible. How many hectares did it plow in one hour (what is it perfor

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