Dr. Mann mixed 10.357 g of chemical A, 12.062 g of chemical B, and 7.506 g of chemical C to make 5 doses of medicine.

a. About how much medicine did he make in grams? Estimate the amount of each chemical by rounding to the nearest tenth of a gram before finding the sum. Show all your thinking.

b. Find the actual amount of medicine mixed by Dr. Mann. What is the difference between your estimate and the actual amount?

c. How many grams are in one dose of medicine? Explain your strategy for solving this problem.

d. Round the weight of one dose to the nearest gram.

The answers are:

a. Estimated amount: 30.0 g.

b. Actual amount: 29.925 g. Difference: 0.075 g

c. Grams by dose: 5.985g

d. Rounded dose to the nearest gram: 6g

Step-by-step explanation:

To round to the nearest tenth you have to check if the hundredths and thousandths places are greater than fifty, then the tenths place is increased by one, else maintains the number.

For:

10.357, 57 > 50, round to 10.4 12.062, 62 > 50, round to 12.1 7.506, 06 < 50, round to 7.5 Sum = 10.4g + 12.1g + 7.5g = 30.0g

b.

Actual amount = 10.357g + 12.062g + 7.506g = 29.925g Difference = 30.0g - 29.925g = 0.075g

c.

Dr. Mann did 5 doses, so you can divide the actual amount by 5.

Dose: 29.925g / 5 = 5.985g

d. Use the same strategy to round, now for the nearest gram.

5.985, 98 > 50, round to 6.