Question

4 mm of Ink A is added to 10 mm of ink B, forming a mixture of inks. Ink A contains 10% blue pigment. Ink B contains an unknown percentage of blue pigment. The mixture of the two inks contain 35% blue pigment. What percentage of blue pigment is in ink B?

• 45%
• 49%
• 60%
• 75%

Answer 1

35% are blue pigment, hence the mixture contains 4.9 mm of blue ink. Ink A contains 10%*4mm=0.4mm of blue ink. 4.5 mm of blue ink must have come from ink B. Thus ink B contains 4.5 mm of blue ink and is in total 10mm. 4.5/10=0.45 and this is the ratio of blue ink to total ink (in Ink B). If we transform it to percentages it is 45

Answer 2

We know that the mixture has 14 mm of ink. Of these, 35% are blue pigment, hence the mixture contains 4.9 mm of blue ink. Ink A contains 10%*4mm=0.4mm of blue ink. The difference, 4.5 mm of blue ink must have come from ink B. Thus ink B contains 4.5 mm of blue ink and is in total 10mm. After that, we can calculate the percentage; we divide 4.5/10=0.45 and this is the ratio of blue ink to total ink (in Ink B). If we transform it to percentages it is 45%