Word Problems/Math

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Question
1. Xuxian and Rachel had the same number of marbles. After Rachel gave away 10 marbles and Xuxian gave away 22 marbles, Rachel had 3 times as many marbles as Xuxian. How many marbles did each of them have at first?

2.  Mr. Tan put up poles from one end of a road to the other at equal distances apart.  There are 27 wooden poles. The width of each pole is 10 cm. The distance etween 2 poles is 30 m. Find the length of the road.

3.  Krishnan had 64 coins in his coin box. There were 20-cent coins and 50-cent coins. The total value of all the coins was $ 18.50. How many 20-cent coins and how many 50-cent coins were there?

Answer
"Xuxian and Rachel had the same number of marbles."
x = r

"After Rachel gave away 10 marbles and Xuxian gave away 22 marbles, Rachel had 3 times as many marbles as Xuxian."
r-10 = 3(x-22)

x-10 = 3(x-22)
x-10 = 3x-66
2x = 56
x = 28

Rachel and Xuxian each had 28 marbles.
:::::
I am assuming that the end poles are centered 5 cm from the ends of the road.

10 cm 1 meter/(100 cm) = 0.1 m
Each pole is 0.1 meter in diameter.

There are 26 spaces between poles. Each space is 30 meters.

Length of road = 27 poles 0.1 meter/pole + 26 spaces 30 meters/space
= 2.7 meters + 780 meters
= 782.7 meters
:::::
"Krishnan had 64 coins in his coin box. There were 20-cent coins and 50-cent coins."
t = number of 20-cent coins
f = number of 50-cent coins
t+f = 64
f = 64-t

"The total value of all the coins was 18.50"
0.20t + 0.50f = 18.50

0.20t + 0.50(64-t) = 18.50
0.20t + 32-0.50t = 18.50
-0.30t = -13.50
t = 13.50/0.30 = 45
f = 64-t = 19

There were forty-five 20-cent coins and nineteen 50-cent coins.

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Janet Yang

Expertise

Word problems are my favorite type of math questions! I would not feel comfortable answering questions that require specialized knowledge (Physics, Statistics, etc.) because I have not studied these in depth.

Experience

I tutor students (fifth through twelfth grades) and am a Top Contributor on Yahoo!Answers with over 24,000 math solutions.

Publications
Co-author of An Outline of Scientific Writing: For Researchers With English as a Foreign Language.

Education/Credentials
I have a Bachelor's degree in Applied Mathematics from the University of California at Berkeley, and a Master of Business Administration degree from The Wharton School.

Past/Present Clients
George White Elementary School. Homework Help program at the Ridgewood Public Library, Ridgewood, NJ. Individual students.

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