gave half of the remaining oranges and another one beside. By this time, John had one orange left. How many did he start with?
2. Ben sold half his fish and half a fish to his friend Jack and still had 22 fish left. How many fish did Ben start with?
3. One pipe fills a tank in 1 hour while another pipe can fill the same tank in 2 hours. How long will it take to fill the tank if both pipes are used.
4. "Best of clocks, how much of the day has gone?" asked Linda. Replied the clock, "There remains one third as much time as has gone." Given the day starts at 12:00 midnight, what is the time?
5. My digital watch shows hours and minutes only. For what fraction of a complete day is at least one "1" showing on the display?
5 hard math problems
- ashkanOo
نام: اشکان
محل اقامت: تهران
عضویت : چهارشنبه ۱۳۹۰/۹/۳۰ - ۱۵:۱۱
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Re: 5 hard math problems
the answers
1. To the second friend , he gave 2 oranges +1 more and had 1 left. so he started with 4. To the first friend he gave 5 + 1 more and had 4 left over. Started with 10
2. half of the total + one half more and ended with 22. Had 45 to begin with.
3. one pipe fills tank in 1 hr and one pipe in 2 hrs. in 40 minutes, first pipe fills tank (2/3 full) and 2nd pipe fills tank 1/3 full. Totla time = 40 minutes
4. 18 hours went by, and 1/3 of 18 (6) remains. Time is 6:00 PM
5. 1Pm 10 - 12 Pm = 3 hours . 10 - 19 minutes = 10 minutes + 1 minute at 01, 21, 31, 41, 51 = 15 minutes each of teh 9 hours not already counted.
180 minutes + 15 (9) = 180 + 135 = 315 divided by 720 minutes (half of the day. The other half is exactly the same)
315/720 = 63/144 = 21/48 = 7/16
1. To the second friend , he gave 2 oranges +1 more and had 1 left. so he started with 4. To the first friend he gave 5 + 1 more and had 4 left over. Started with 10
2. half of the total + one half more and ended with 22. Had 45 to begin with.
3. one pipe fills tank in 1 hr and one pipe in 2 hrs. in 40 minutes, first pipe fills tank (2/3 full) and 2nd pipe fills tank 1/3 full. Totla time = 40 minutes
4. 18 hours went by, and 1/3 of 18 (6) remains. Time is 6:00 PM
5. 1Pm 10 - 12 Pm = 3 hours . 10 - 19 minutes = 10 minutes + 1 minute at 01, 21, 31, 41, 51 = 15 minutes each of teh 9 hours not already counted.
180 minutes + 15 (9) = 180 + 135 = 315 divided by 720 minutes (half of the day. The other half is exactly the same)
315/720 = 63/144 = 21/48 = 7/16
B.Sc physics at amirkabir university of tehran