SOLUTION: if i am going 45mph and i am a 1/2 a mile ahead of the other person, how fast would the other person be going to catch me in appr. 1 minute? And please show me the formula you use.

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Question 777950: if i am going 45mph and i am a 1/2 a mile ahead of the other person, how fast would the other person be going to catch me in appr. 1 minute? And please show me the formula you use. THANKS
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
You have head start of +1%2F2+ mi
Start a stop watch when the 2nd person is
+1%2F2+ mi behind.
Let +1%2F60+ = the time in hours on the stop watch
when the 2nd person catches the 1st
Let +d+ = the distance in miles the 2nd person
travels until catching the 1st person
Let +r+ = the rate in mi/hr of the 2nd person
--------------------------
1st person's equation:
(1) +d+-+1%2F2+=+45%2A%281%2F60%29+
2nd person's equation:
(2) +d+=+r%2A%281%2F60%29+
------------------
By substitution,
+r%2A%281%2F60%29+-+1%2F2+=+45%2A%281%2F60%29+
Multiply both sides by +60+
+r+-+30+=+45+
+r+=+75+
The 2nd person must travel 75 mi/hr
--------------
check:
(2) +d+=+r%2A%281%2F60%29+
(2) +d+=+75%2A%281%2F60%29+
(2) +d+=+1.25+ mi
and
(1) +d+-+1%2F2+=+45%2A%281%2F60%29+
(1) +d+=+45%2F60+%2B+30%2F60+
(1) +d+=+75%2F60+
(1) +d+=+1.25+ mi
OK