SOLUTION: I need to figure out a way to solve this type of questions, please help!! When multiplying two numbers, you increase (or decrease) one number by (let's say) 20%, and increase (o

Algebra ->  Percentages: Solvers, Trainers, Word Problems and pie charts -> SOLUTION: I need to figure out a way to solve this type of questions, please help!! When multiplying two numbers, you increase (or decrease) one number by (let's say) 20%, and increase (o      Log On


   

Question 587758: I need to figure out a way to solve this type of questions, please help!!
When multiplying two numbers, you increase (or decrease) one number by (let's say) 20%, and increase (or decrease) the other by (let's say) 30%, by what % will the final product change?
Thanks!
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Say one number is 7
7 increased by 20% is +7+%2B+.2%2A7+=+1.2%2A7+
Say the other number is 13
13 increased by 30% is +13+%2B+.3%2A13+=+1.3%2A13+
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Now to multiply these:
+%281.2%2A7%29%2A%281.3%2A13%29+
You can rewrite this as
+%281.2%2A1.3%29%2A%287%2A13%29+
+1.56%2A%287%2A13%29+
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I just picked any 2 numbers, so you would have +1.56+
times whatever numbers you pick