SOLUTION: As Carlos improves his algebra skills, he takes 0.6 times as long to complete each homework assignment as he took to complete the preceding assignment. If it took him 75 minutes to

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Question 1060261: As Carlos improves his algebra skills, he takes 0.6 times as long to complete each homework assignment as he took to complete the preceding assignment. If it took him 75 minutes to complete his first assignment, find how long it took him to complete the fifth assignment. Find the total time he took to complete his first five homework assignments (Round to the nearest minute.)
A. 10 min; 173 min
B. 10 min; 104 min
C. 6 min; 104 min
D. 6 min; 173 min
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The equation is:
+T%28n%29+=+T%5B0%5D+%2A%28+.6+%29%5En+
where +n+ is the number of the assignment
( +n+ has to start with +0+, so that
+T%280%29+=+T%280%29+ )
-------------------
+T%5B0%5D+=+75+
+n=+4+ ( that would be the 5th assignment
since I started with +0+ )
-------------------
+T%284%29+=+75%2A.6%5E4+
+T%284%29+=+75%2A.1296+
+T%284%29+=+9.72+ min for 5th asignment
-----------------------
+T%280%29+=+75+
+T%281%29+=+45+
+T%282%29+=+27+
+T%283%29+=+16.2+
+T%284%29+=+9.72+
-------------------
Total time = +172.92+
The answer is A.