Question 1210620: Fill in the blanks to make a true statement.
If we increase a by 10%, then we obtain b. If we increase b by 10%, then we obtain c. Overall, we can obtain c by increasing a by ___ %.
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39823)   (Show Source):
Answer by greenestamps(13355)  (Show Source):
You can put this solution on YOUR website!
A general discussion....
If a number x is increased by 13%, then the new number is x plus 13% of x, or
In most problems, percent increases (and percent decreases) are more easily thought of using multiplication instead of addition or subtraction. So instead of adding 13%, we multiply by 1.13.
This use of multiplication instead of addition or subtraction has HUGE advantages if the problem involves multiple successive percent increases and/or percent decreases.
Similarly, if we know that a number is 1.13 times its previous value, then we know the old number was increased by 13%.
In this problem, we have two consecutive increases of 10%. That means multiplying the original number by 1.10 (or just 1.1) and then multiplying it by 1.1 again. So
b = 1.1(a)
c = 1.1(b) = (1.1)(1.1)(a) = 1.21(a)
And from this we see that the overall increase is 21%.
ANSWER: 21%
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