Question

A jeweller is selling 22-carat gold articles with 95% purity, it is approximately:
(A) Exact
(B) 3.5% higher
(C) 3.5% lower
(D) 5% lower

Answer 1

Hint: The purity of the gold can be given in carats. 24-carat gold is expected to be 100% pure. We can compare the purity of 22-carat gold with the purity of gold the jeweller is selling in order to get the answer.

Complete step by step solution:
The purity of the gold articles can be given in carats. Here, we are given that the jeweller is selling the 22-carat articles.
- Gold with 100% purity is also referred to as 24-carat gold. It means that there is no other element present in the material than gold. 100% pure gold is a soft material and it cannot be used to make ornaments because it cannot hold the shape for a longer time as the material is soft.
- 22-carat gold is a little less pure than the 24-carat gold. Here, alongside Gold, other metals like copper are also added. This material is hard enough that we can use them in making ornaments.
Now, we will calculate the purity of the 22-carat gold.
We know that the purity of 24-carat gold is 100%. So, the purity of 22 carat gold will be $\dfrac{{22}}{{24}} \times 100 = 91.66\% $
Thus, we obtained that the purity of 22-carat gold is 91.66%.
Now, the jeweller is selling the gold of 95% purity.
So, the jeweler is giving 95% - 91.66% = 3.5% higher purity.

Therefore, the correct answer to this question is (B).

Note: There are two main ways of expressing the fineness of precious metals. One is in carats which is a fractional measure of the purity of gold alloys. It is used only for gold. The other method is the millesimal fineness. It denotes the fineness of purity of the metal by parts per thousand.