SOLUTION: Isabella saved 2 nickels today. If she doubles the number of nickels she saves each day, how many days, including today will it take her to save more than 500 nickels

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Question 1056491: Isabella saved 2 nickels today. If she doubles the number of nickels she saves each day, how many days, including today will it take her to save more than 500 nickels
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
day 1: +2%5E1+
day 2: +2%5E1+%2B+2%5E2+
day 3: +2%5E1+%2B+2%5E2+%2B+2%5E3+
day 4: +2%5E1+%2B+2%5E2+%2B+2%5E3+%2B+2%5E4+
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Doing the math:
day 1: +2+
day 2: +2+%2B+4+=+6+
day 3: +2+%2B+4+%2B+8+=+14+
day 4: +2+%2B+4+%2B+8+%2B+16+=+30+
---------------------------------
After +n+ days shw has saved +2%5E%28+n%2B1+%29+-+2+ nickels
+2%5E%28+n%2B1+%29+-+2+%3E+500+
+2%5E%28+n%2B1+%29+%3E+502+
I can take the log base 10 of both sides
+%28+n+%2B+1+%29%2Alog%282%29+%3E+log%28+502+%29+
+n+%2B+1+%3E+log%28+502+%29+%2F+log%28+2+%29+
+n+%2B+1+%3E+2.7007+%2F+.30103+
+n+%2B+1+%3E+8.971+
+n+%3E+7.971+
It will take 8 days to save more than 500 nickels
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check:
+2+%2B+4+%2B+8+%2B+16+%2B+32+%2B+64+%2B+128+%2B+256+=+510+
Ok
By all means get another opinion, also