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Showing posts from June, 2010

Street Math: How to get spoon and fork in food courts efficiently

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Problem In many food courts (at least in the Philippines), spoons and forks are usually kept in a 2x2 container (2 rows and 2 columns), such as the one shown below.   What would be the optimal way of getting utensils such that the probability of getting 2 of the same kind (2 spoons or 2 forks, instead of 1 spoon and 1 fork) is kept to a minimum? Solution Get the utensils which are oriented diagonally to each other. Why it works   There is a great chance that the spoons and forks will be alligned in a row or a column (human psychology, perhaps?). Thus, getting the utensils which are oriented diagonally to each other will most likely yield utensils which are not of the same type. Comment s I have been using this principle for a long time already and I have only failed once. Whenever I am able to get 1 spoon and 1 fork correctly, there is some feeling of gratification.  You should try it next time you are in a food court! Image from : http://www.ebay.com.au/itm/Cutlery

Everyday Math: How to know how many pages there are from StartPage to EndPage

Here is a simple calculation for everyday living. Problem You want to print pages 23-45 of a file. How many pages will you make? Solution Formula: EndPage-StartPage+1 Example Printing pages 23-45 will produce (45-23)+1 =23 pages

Everyday Math: How to know what time it would it be x hours from now

Here is a simple calculation for everyday living. Examples: What time would it be 7.5 hours after 9:30AM? What time would it be 8 hours after 10:30AM? Solution 1. Compute CurrentTime+TimeToElapse 2. If the Sum is less than or equal to 12:00, the Sum is your answer. 3. If the Sum is more than or equal to 12:00: a. Subtract 12:00 from the Sum b. Switch from AM to PM or PM to AM depending on the which side CurrentTime is Examples Example1 7.5 hours after 2:00PM 2:00+7:30=9:30PM (we don't switch from PM to AM since the Sum is less than 12:00) Example2 7.5 hours after 9:30AM 9:30+7:30=17:00 17:00 is greater than 12:00   So we subtract 12:00 from the Sum -> 17:00-12:00=5:00 Then we switch from AM to PM Therefore the answer is 5:00PM Example3 8 hours after 10:30AM 10:30+8:00=18:30 18:30-12:00=6:30 Switch from AM to PM: Answer is 6:30PM

Everyday Math: How to know the time elapsed between StartTime and EndTime

Here is a simple calculation for everyday living. Problem How many hours are there from 9:30PM to 5:00AM, without running the hours in your fingers? What about from 10:30AM to 4:00PM? Solution Case 1 If both StartTime and EndTime are in the AM or PM, simply subtract StartTime from EndTime Example Start Time: 8:00AM ; End Time 11:30AM   Time Difference-> 11:30-8:00= 3 hours 30 mins Case 2 If one is in the AM, the other in the PM Formula: (12:00- Start Time) + End Time Example 1 Start Time: 9:30PM ; End Time 5:00AM   Time Difference: (12:00-9:30)+5:00 = 7hours 30mins Example 2 Start Time: 10:30AM ; End Time 4:00PM   Time Difference: (12:00-10:30)+4:00 = 5hours 30mins

Everyday Math: How to know whether it is the 1st, 2nd, etc. day of the month

Here is a simple calculation for everyday living. Problem There are events, meetings that sometimes happen on the 1st, 2nd,3rd or 4th day of the month. For example, some activities could be held every 2nd Sunday of the month or 4th Monday of the month. So how do you know that a date is the 2nd Monday or 4th Sunday of the month? Solution Divide the date by 7. If the quotient is a whole number, that's your answer. If it's not, the answer is obtained by rounding the quotient to the next whole number. Examples Example 1 December 14 is a Monday;   14/7=2; 2 is a whole number.   So December 14 is the   2 nd Monday of the month. Example 2 Today is Sunday, October 25.   25/7= 3. something 3. something   is not a whole number, so round it up to the next whole number, which is 4. So October 25 is the   4 th Sunday of the month. Notes In technical terms, the formula is Ceiling(Date/7) where Ceiling is a function that rounds up non-whole numbers to the nex