About Soroban Expertise I have a systematic and orderly way to organize the facts in a word problem, which (usually) leads clearly to the necessary equation. I think I can help with all types of word problems.
Experience 38 years of teaching college-level math, mostly at a two-year college.
Education/Credentials BS and MS in mathematics, SUNY Albany
Expert: Soroban Date: 2/21/2008 Subject: Related Rates problem...
Question A lighthouse is at point A, 5km North offshpre from the nearest point O of a straight beach. A store is at point C 7 km East of point O. If a man can row 4km/hr and walk 5km/hr, how should he proceed in order to get from the light house to the store in the least possible time?
NOTE that the figure is a right triangle.
Answer Hello, Kim!
This is a classic problem, found in every Calculus book.
By the way, it's not "related rates" problem.
It is an Optimization (max/min) problem.
Try to follow my diagram.
Draw a horizontal line: O at the left end, C at the right end.
OC = 7 km
From O draw a line straight up to A.
AO = 5 km
Halfway between O and C, mark point P (on the line).
Label OP with x . . . then PC = 7 - x
