Q: Which of the following is the correct formula for calculating the variance of a sample?

$$\text{Variance} = \frac{\sum_{i=1}^{N}(x_i - \bar{x})^2$}{N-1}$$

Question 1

Which of the following best describes the difference between accuracy and precision in scientific measurements?

Accepted Answer

Accuracy refers to how close measurements are to the true value, while precision refers to how close measurements are to each other.

Question 2

A scientist measures the length of a leaf five times and gets the following values (in cm): 8.1, 8.2, 8.1, 8.2, 8.1. The actual length is 7.5 cm. Which statement is correct?

Accepted Answer

The measurements are precise but not accurate.

Question 3

Which metric unit would be most appropriate to measure the mass of a housefly?

Accepted Answer

Milligram (mg)

Question 4

Convert 3.1 kilograms to milligrams.

Accepted Answer

$$3.1 	imes 10^6$ mg

Question 5

A graduated cylinder contains 70 mL of water. After a rock is submerged, the water level rises to 85 mL. What is the volume of the rock?

Accepted Answer

$$15 mL$$

Question 6

Which of the following is the correct way to read the volume of a liquid in a graduated cylinder?

Accepted Answer

At the bottom of the meniscus, with your eye level to the meniscus

Question 7

A student measures the mass of a rock as 25 g and its volume as 10 mL. What is the density of the rock?

Accepted Answer

$$2.5 g/mL$$

Question 8

Which of the following is NOT a base unit in the metric system used in biology?

Accepted Answer

Inch (in)

Question 9

A thermometer reads 22°C. What is this temperature in degrees Fahrenheit? (Use $$5(°F) = 9(°C) + 160)$$

Accepted Answer

$$71.6^{\circ}F$

Question 10

Which of the following best explains why the mean may not always represent a 'typical' value in a biological sample?

Accepted Answer

The mean is affected by extreme values (outliers) in the sample.

Question 11

Given the following data set: 10, 12, 14, 16, 100. What is the median?

Accepted Answer

14

Question 12

Which of the following is the correct formula for calculating the variance of a sample?

Accepted Answer

$$	ext{Variance} = \frac{\sum_{i=1}^{N}(x_i - \bar{x})^2$}{N-1}$$

Question 13

If a sample has a mean of 20 and a standard deviation of 2, what range of values would include approximately 68% of the measurements?

Accepted Answer

18 to 22

Question 14

Which of the following is a potential source of error in biological measurements?

Accepted Answer

All of the above

Question 15

A student records the following masses for a sample: 1.2 g, 1.3 g, 1.2 g, 1.3 g. The true mass is 1.8 g. Which statement is correct?

Accepted Answer

The measurements are precise but not accurate.

Question 16

Which prefix represents one millionth ($$10^{-6}) of a $$base metric unit?

Accepted Answer

Micro-

Question 17

A sample of four apples has masses: 25 g, 35 g, 32 g, 28 g. What is the mean mass?

Accepted Answer

30 g

Question 18

Which of the following best describes the use of significant figures in biological measurements?

Accepted Answer

Include all digits you are sure of plus one estimated digit.

Question 19

Why is it important to use the metric system in scientific measurements?

Accepted Answer

It is based on units of ten, making conversions easier and improving communication among scientists.

Question 20

A scientist wants to measure the volume of a small irregularly shaped stone. Which method should they use?

Accepted Answer

Water displacement in a graduated cylinder

Measurements in Biology: The Metric System and Data Analysis

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