Question

Identify the numbers in each of the following statements as measured or exact:

(Write a BRIEF explanation for how you got your answer.)

a. There are 31 students in the laboratory.

b. The oldest known flower lived 1.20 x 10/8 yr ago.

c. The largest gem ever found, an aquamarine, has a mass of 104 kg.

d. A laboratory test shows a blood cholesterol level of 184 mg/dL.

Answer 1

a) The number of students in the laboratory is exact. You have records of the students which show that exactly 31 students enrolled for the lab. Moreover, you can count the number of students without any ambiguity.

b) The age of the oldest known flower is measured. Offcourse, modern man and modern scientific methods weren’t existent about 1.20*10⁸ years ago (which is much more than 1 million years ago). Scientific methods allow us to do experiments and measure the age of the flower using mathematical formula.

c) The weight of the largest gem is measured. The weight was definitely measured with some kind of balance. Weighing balances are known to have certain uncertainty associated with the measurement and the weighing also depends on a number of physical factors like humidity, accuracy of the experimenter, etc. The same gem may weigh 103 kg or 105 kg on a separate balance and in a separate country.

d) The blood cholesterol level is measured suing experiments and calculations. There may be a number of different methods of measuring blood cholesterol; moreover, the results will vary from lab to lab since the results are dependent on temperature, humidity, etc.