







Differentiate x^x  2^sinx 
20130809 

From tarun: derivative of x^x  2^sinx Answered by Penny Nom. 





What percent is 50 of 4.5 billion? 
20130808 

From Bobby: What percent is 50 from 4.5 billion? Answered by Penny Nom. 





Four equations 
20130808 

From may: HI how to solve this 4 equations?
A+C = 0
4A+B8C+D=1
3A+16C8D=29
12A+3B+16D=5 Answered by Robert Dawson. 





Practical uses of trigonometry 
20130806 

From tharindu: use of trigonometry Answered by Penny Nom. 





Slicing through a cone to form an ellipse 
20130806 

From Pulkit: we get an ellipse on slicing through a cone. Is there a relation between central axis of the cone and this ellipse?
Does it pass through the any of the foci of the ellipse? Answered by Chris Fisher. 





Squares and cubes 
20130802 

From Sandra: What whole number equals 25 when it is squared and 125 when it is cubed? Answered by Penny Nom. 





A golf tournament for 12 people 
20130801 

From Brad: I've looked all over the web for a solution to this (including searching the archives here) to no avail.
We're doing a golf tournament with twelve people. Each person has a "handicap" that demonstrates their skill level. We have these numbers for each of the 12 players. We are trying to figure out how to schedule two rounds of golf with the most balance possible.
 We are playing two "real" rounds of golf (18 holes). There are four people per group.
 We want to split each round into two 9 hole games, which gives us a total of 4 games
 Halfway through (after 9 holes), you switch partners within the foursome that you're playing in.
 We want everyone to play with 4 unique different teammates
So say you start the first 18 hole round as a group of Players 1, 2, 3, and 4. Players 1 and 2 are a team, and players 3 and 4 are a team. After 9 holes, Player 1 would either be paired up with Player 3 or 4, and the other two players would pair up as well. Then the next day we will mix up the foursomes and do the same thing.
In terms of just pure scheduling this is simple. But I'm trying to figure out how to best balance the handicaps (simple average of each team's two handicaps works here). Assuming I'll need some sort of program or spreadsheet.
Any help or even a push in the right direction would be a tremendous help. Thanks in advance to anyone who wants to give this a shot. Answered by Victoria West. 





Golf for 16 
20130731 

From Graylin: I am going on a golf trip and we have 16 players and need to know a formula that will allow us to all play together at some point in the 4 rounds we are playing. If not possible please provide best case.
Thanks. Answered by Victoria West. 





16 golfers 
20130731 

From Pat: 16 golfers...3 nine hole rounds a day...for 4 days.
what are the best pairings for the fewest repeats of partners? Answered by Victoria West. 





Dilution of concentrated acid 
20130731 

From Adom: I have 500mls of 90% conc. of an acid. Now I need to prepare 20% concentration from this (say 100mls of this). How much of the stock solution do I take and how much water to add? Thanks! Answered by Penny Nom. 





Two parallel chords of a circle 
20130730 

From Don: two parallel chords of a circle AB and CD on the same side from the center measure 6cm and 11 cm respectively. The distance between the 2 chords is 3 cm. Find the radius Answered by Penny Nom. 





A mixture problem 
20130729 

From Lucy: Hi,
For the following question:
Ten pounds of mixed nuts contain 50 percent peanuts. How many pounds of peanuts must be added so that the final mixture has 60 percent peanuts?(A) 2.5 (B) 5 (C) 6 (D) 10 (E) 12.5,
my math book gives my the following explanation: Try choice (C): 6 pounds of peanuts. The original 10pound mixture contained 50 percent peanuts, or 5 pounds. Now you have 11 pounds of peanuts in a 16pound mixture, more than 60 percent. This result automatically eliminates choices (D) and (E) as well.Why would this result automatically rule out D and E? How can you tell?
Thank you for taking the time to answer my question. Answered by Robert Dawson and Penny Nom. 





A word problem 
20130729 

From Gontsejalo: Your firm held a dance competition. 900 people attended the dance competion.The cost of admission was 20rand per person and 30,50rand per couple.Twice as mant 20rand tickets as 30,50rand tickets were sold.find the amount of money obtained from the tickets sales Answered by Penny Nom. 





Working backwards 
20130728 

From Petal: Tom bought some oranges. He threw 37 rotten oranges and bought 56 more. Finally he had 220 oranges. How many oranges did Tom had at first? Answered by Penny Nom. 





The area of a semicircle 
20130728 

From Lucy: Find the area of the the figure described: a semicircle with arc length 3 pi. Answered by Penny Nom. 

