
Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion 
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March 24th, 2009, 03:10 AM  #1 
Joined: Mar 2009 Posts: 1 Thanks: 0  percentage % of a number
okay i'm currently studying for a ASVAB test for the military. and they have questions like the one below, " what number is 5% of 2000 " how would i solve for something like that? or they have " 35% of what number is 70 " " if 45 is 120% of a number, what is 80% of the same number? " " if 6 is 24% of a number, what is 40% of the same number? " " 25% of $900= " questions like those, please help! 
March 24th, 2009, 06:15 AM  #2 
Global Moderator Joined: Dec 2006 Posts: 11,318 Thanks: 271 
The symbol "%" means "hundredths", so 120% means 120/100 or 1.2, and 5% is 5/100 or 1/20 or 0.05. Hence, in particular, "50%" means "half", "100% of" means "all", "200% of" means "twice", etc. For problems such as "What number is 5% of 2000?" (or "Find 5% of 2000."), just multiply 0.05 by 2000 to get the answer. The problem "35% of what number is 70?" corresponds to the equation: (35/100) * x = 70, where x is the number to be found. Dividing both sides of this equation by 0.35 gives x = 70/0.35. Does this help you enough for you to complete these problems and do the remaining problems? 
March 25th, 2009, 04:15 PM  #3 
Joined: Jul 2008 Posts: 895 Thanks: 0  Re: percentage % of a number
Write it literally [word for word]. The = sign is the verb in the sentence, and "of" means "times", or "multiply", as in three quarters of 12 is 9 ... 3/4x12 = 9. " what number is 5% of 2000 " N = 5/100x2000 = 100 " 35% of what number is 70 " 35/100xN = 70 Solve for N ...You must be able to do some algebra from past experience. If not, start again. " if 45 is 120% of a number, what is 80% of the same number? " 45 = 120/100xN Solve for N, then find 80% of N. etc... 
March 26th, 2009, 02:48 AM  #4  
Global Moderator Joined: Dec 2006 Posts: 11,318 Thanks: 271  Quote:
 
March 26th, 2009, 04:31 AM  #5  
Joined: Jul 2008 Posts: 895 Thanks: 0  Re: Quote:
6 is 24% of a number 6 = 24/100xN N = 6x100/24 = 25 what is 40% of the same number? N1 = 40/100xN = 40/100x25 = 10  
March 28th, 2009, 03:52 AM  #6 
Global Moderator Joined: Dec 2006 Posts: 11,318 Thanks: 271 
No reason why not. I was giving a process suited to mental arithmetic (as I understand it, the ASVAB is a multiple choice test).

March 28th, 2009, 04:12 AM  #7  
Joined: Jul 2008 Posts: 895 Thanks: 0  Re: Quote:
 

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