Question

Lisa has a tube of Kinney's suntan lotion that is rated 15 spf and a second tube of Copper-tone that is 30 spf. How many fluid ounces of each type of lotion should be mixed in order to create 50 fluid ounces of sunblock that is rated 20 spf?

Answer 1

To create a 50 fluid ounce sunblock with SPF 20, mix 20 fluid ounces of Kinney's lotion and 30 fluid ounces of Copper-tone lotion.

Step-by-step explanation:

To create 50 fluid ounces of sunblock that is rated 20 SPF, we can use a mixture of Kinney's suntan lotion and Copper-tone lotion. Let's assume we need x fluid ounces of Kinney's lotion and (50 - x) fluid ounces of Copper-tone lotion.

The SPF of a mixture can be calculated using the formula:
SPFMixture = (x * SPF_Kinney + (50 - x) * SPF_CopperTone) / 50

Substituting the given information into the formula, we get 20 = (15x + 30(50 - x)) / 50. Solving this equation, we find x = 20 fluid ounces of Kinney's lotion and (50 - x) = 30 fluid ounces of Copper-tone lotion should be mixed to create a 50 fluid ounce sunblock with SPF 20.

Learn more about mixing lotion to create sunblock