A scientist has a sample of the radioactive isotope bismuth-212. The isotope decays exponentially as shown in the table. Time (seconds) Mass (grams) 10 26.8 20 23.9 30 21.3 40 19.0 50 16.9 60 15.1 What was the approximate mass of the original sample? A. 27 grams B. 28 grams C. 29 grams D. 30 grams

in problems involving proportions, we can use cross products to test whether two ratios are equal and form a proportion. to find the cross products of a proportion, we multiply the outer terms, called the extremes, and the middle terms, called the means.

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536

step-by-step explanation:

85.3-64 = 21.3

so laura has already added 85.3 grams of chocolate powder and she has gone over the amount specified in the recipe by 21.3 grams

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