Question

locating information in difficult graphics
approximate colors of jewelry alloys
gold (au)
green
yellow
20
30
40
50
60
70
80
90
silver (ag)
10 20 30 40 50 60 70 80 90
copper (cu)
wt %cu
a jewelry maker uses different combinations of alloys to
change the appearance of jewelry.
what percentage of gold must be added to a mixture of
30 percent silver and 30 percent copper to produce a
yellowish color?
10 percent
30 percent
40 percent
80 percent

Explanation:

Step1: Analyze the total percentage

The total percentage of the mixture should be 100%. We know silver is 30% and copper is 30%. Let the percentage of gold be \( x \). So, \( 30 + 30 + x = 100 \).

Step2: Solve for x

Simplify the equation: \( 60 + x = 100 \). Subtract 60 from both sides: \( x = 100 - 60 = 40 \). Also, from the graph, the yellowish region for gold (Au) has a percentage that matches this calculation.

Answer:

40 percent (the option: 40 percent)