Question

5 The probabilities of a boy passing English and Mathematics tests are a and b respectively. Find the probability of the boy failing both tests.
1-(a+b)+ab
1-(a+b)-ab
1-(a+b)
1-(a-b)-ab
6 Statistics is a descriptive measurement obtained from a ----------------
observation
sample
experiment
population
7 The grade of student on six examinations were 84, 91, 72, 68, 87, and 78. What is the arithmetic mean of the grades?
88
60
70
80
8 The scores of 5 students in an examination are: 6, 5, 8, 7 and 4. Find the variance.
3
2
2.5
4.5
9 The scientific method for collection, summarization, presentation, analysis and interpretation of data is called
statistics
investigation
biostatistics
questionairing
10 A ............. is the total collection of all the possible outcomes of an experiment
Sample space
Sample
Experiment
Statistics

Answer 1

Answer on Question #616128 – Math – Statistics and Probability

Question

5. The probabilities of a boy passing English and Mathematics tests are a and b respectively. Find the probability of the boy failing both tests.

Solution

If the probability of a boy passing English and Mathematics tests are a and b respectively, then the probability of the boy falling English is $(1 - a)$, and the probability of the boy falling Mathematics is $(1 - b)$. So the probability of the boy falling both tests is

$$P = (1 - a)(1 - b) = 1 - a - b + ab = 1 - (a + b) + ab$$

Answer: $1 - (a + b) + ab$

Question

6. Statistics is a descriptive measurement obtained from a ________ observation sample experiment population

Solution

Statistic (not to be confused with Statistics) - Characteristic or measure obtained from a sample.

Statistics - Collection of methods for planning experiments, obtaining data, and then organizing, summarizing, presenting, analyzing, interpreting, and drawing conclusions.

Answer: sample.

Question

7. The grade of student on six examinations were: 84, 91, 72, 68, 87, and 78.

What is the arithmetic mean of the grades?

88

60

70

80

Solution

The arithmetic mean of the grades is

$$\frac{84 + 91 + 72 + 68 + 87 + 78}{6} = 80.$$

Answer: 80.

Question

8. The scores of 5 students in an examination are:

6, 5, 8, 7 and 4.

Find the variance.

3

2

2.5

4.5

Solution

$$\sum x_i = 6 + 5 + 8 + 7 + 4 = 30.$$ $$\overline{x} = \frac{\sum x_i}{n} = \frac{30}{5} = 6.$$ $$\sum x_i^2 = 6^2 + 5^2 + 8^2 + 7^2 + 4^2 = 190.$$

The variance is

$$\sigma^2 = \frac{\sum x_i^2 - n \overline{x}^2}{n} = \frac{190 - 5 \cdot 6^2}{5} = 2.$$

Answer: 2.

Question

9. The scientific method for collection, summarization, presentation, analysis and interpretation of data is called ______.

- statistics

- investigation

- biostatistics

- questioning

Answer: statistics.

Question

10. A ______ is the total collection of all the possible outcomes of an experiment

- Sample space

- Sample

- Experiment

- Statistics

Answer: sample space.

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