You are here:

# Algebra/Algebra II/ Trig Honors word problem

Question
Varun has five rings, each weighing 18 g, made of an alloy of 10% silver and 90% gold. He decides to melt down the rings and add enough silver to reduce the gold content to 75%%. How much silver should he add?

The answer is 18 g of silver but I'm not sure how to get to that answer.

Total amount of gold in all 5 rings = 90/100 * 18 * 5 =81 g

Total amount of silver in all 5 rings = 10/100 * 18 * 5 =9 g

Let the required amount of silver to be added to dilute the gold content to 75% be x g.

Then 81/(x + 18*5)= 75/100    (Note: x+18*5 denotes the new overall total amount of alloy)

81/(x + 90 )= 75/100

x+ 90 =108

Therefore, x = 18 g (shown)

Hope this helps. Peace.

Algebra

Volunteer

#### Frederick Koh

##### Expertise

I can answer questions concerning calculus, complex numbers, vectors, statistics , algebra and trigonometry for the O level, A level and 1st/2nd year college math/engineering student.

##### Experience

More than 7 years of experience helping out in various homework forums. Latest presence is over at http://www.thestudentroom.co.uk/. You can also visit my main maths website http://www.whitegroupmaths.com where I have designed "question locker" vaults to store tons of fully worked math problems. A second one is currently being built. Peace.

Organizations
IEEE(Institute of Electrical and Electronics Engineers )

Education/Credentials
Former straight As A level student from HCJC (aka HCI); scored distinctions in both C and Further Mathematics B Eng (Hons) From The National University Of Singapore (NUS) B Sc (Hons) From University of London External (Grad Route)