Lab Midterm Practice

Which of the following are characteristics of a normal distribution?

• It is symmetrical and bell-shaped

• It is symmetrical with two peaks

• The mean is located at the center of the distribution

• It extends to infinity in both directions on the x axis

The ____, or average, is calculated by adding up all of the individual values, then dividing by the total number of values.

Calculate the mean of this dataset:

3, 4, 2, 7, 4,

• 3
• 5
• 6
• 4

Answer explanation

data: 3, 4, 2, 7, 4 (5 individual values)

3 + 4 + 2 + 7 + 4 = 20

20 / 5 = 4 = mean

What value is calculated using this formula?

• mean

• standard deviation

• median

• mode

The _____ group is used for comparison, so it is not tested with the independent variable.

The degree to which an image is enlarged by a lens is called ______.

How do you calculate total magnification?

• Total Magnification = Magnification of Objective Lens / Magnification of Ocular Lens

• Total Magnification = Magnification of Objective Lens x Magnification of Ocular Lens

• Total Magnification = Magnification of Objective Lens

• Total Magnification = Magnification of Ocular Lens

T/F: When using an objective lens with a 10x magnification, total magnification is 10.

• True

• False

Answer explanation

Total = objective x ocular

In a compound microscope, the ocular lens is 10x. Therefore, regardless of the objective lens used, you need to multiply that value by 10 to get total magnification.

If objective is 10x:

total = 10 x 10 = 100 times

What is resolving power (aka resolution) of a lens?

• The extent to which details of the specimen are preserved

• The degree to which an image is enlarged

• The degree to which details stand out against a background

Answer explanation

The extent to which details of the specimen are preserved = resolution

The degree to which an image is enlarged = magnification

The degree to which details stand out against a background = contrast

T/F: Microorganisms are ubiquitous, meaning that they are found everywhere.

• True

• False