Statistics Final Assessment | Homework Practice

Core Concepts

Question 1mcq

A grouped table has intervals

5-15,15-25,25-35

. What is the class width?

A.

30

B.

10

C.

5

D.

15

Question 2mcq

The class mark of

60-80

is:

A.

70

B.

20

C.

60

D.

80

Question 3mcq

If

\sum f_i x_i=900

and

\sum f_i=25

, the direct-method mean is:

A.

25

B.

40

C.

875

D.

36

Question 4mcq

If assumed mean

a=25

,

\sum f_i d_i=60

, and

\sum f_i=20

, find the mean.

A.

25

B.

30

C.

28

D.

22

Question 5mcq

In step-deviation,

a=50

,

h=5

,

\sum f_i u_i=-12

,

\sum f_i=30

. Find mean.

A.

38

B.

48

C.

52

D.

49

Question 6mcq

Which method is best when class widths are equal and deviations have common factor

h

?

A.Step-deviation method

B.Only direct method

C.Median method

D.Mode method

Median and Mode

Question 7mcq

Frequencies

4,6,10

have cumulative frequencies:

A.

4,6,10

B.

20,16,10

C.

10,16,20

D.

4,10,20

Question 8mcq

If total frequency is

80

, the median class contains which observation?

A.The

80

th observation

B.The

160

th observation

C.The

40

th observation

D.The

20

th observation

Question 9mcq

For grouped median,

l=30

,

N=60

,

cf=24

,

f=12

,

h=10

. Find median.

A.

45

B.

35

C.

30

D.

40

Question 10mcq

The class with the highest frequency is called the:

A.Modal class

B.Median class

C.Mean class

D.Class mark

Question 11mcq

For

l=40

,

f_1=20

,

f_0=12

,

f_2=16

,

h=6

, the grouped mode is:

A.

40

B.

46

C.

48

D.

44

Question 12mcq

Which measure is most affected by one extremely high value?

A.Mode

B.Class width

C.Mean

D.Median

Applications

Question 13mcq

A school groups marks into intervals and wants the average score. Which measure should be computed?

A.Sample space

B.Mean

C.Mode only

D.Class width only

Question 14mcq

Which is a common error in grouped median calculation?

A.Using frequency of previous class instead of cumulative frequency before median class

B.Writing units

C.Finding class marks

D.Adding frequencies

Question 15mcq

For class marks

10,20

with frequencies

3,2

, what is the mean?

A.

15

B.

30

C.

20

D.

14

Question 16mcq

In the formula

Median=l+\frac{N/2-cf}{f}\times h

, what is

h

?

A.Median class frequency

B.Lower limit

C.Class width

D.Total frequency

Question 17mcq

Which frequencies are used around the modal class in the mode formula?

A.Only class marks

B.Previous, modal and next class frequencies

C.Only total frequency

D.Only cumulative frequencies

Question 18mcq

A distribution has two equally high frequency classes. What should be checked before applying the mode formula?

A.Whether there is a single clear modal class

B.Whether mean is zero

C.Whether class marks are negative

D.Whether probabilities add to one

Error Analysis

Question 19mcq

A factory records worker wages in grouped intervals. Which pair of measures helps compare typical wage and most common wage range?

A.Radius and tangent

B.Sample space and event

C.Arc and sector

D.Mean and mode

Question 20mcq

If intervals are

0-10,10-20,20-30

, using class widths

10,20,30

is wrong because:

A.Class marks cannot be found

B.Median cannot exist

C.Class width is constant at

10

for each interval

D.Frequency must be zero

Question 21mcq

Which formula finds the class mark of

a-b

?

A.

\frac{b-a}{2}

B.

\frac{a+b}{2}

C.

b-a

D.

a+b

Question 22mcq

If cumulative frequencies end at

75

, what is the total frequency

N

?

A.

75

B.

37.5

C.The first frequency

D.The class width

Question 23mcq

When class marks and frequencies are small, which mean method is straightforward?

A.Only mode formula

B.Only median formula

C.Complement method

D.Direct method

Question 24mcq

A student writes the median class as the class with highest frequency. What concept is being confused?

A.Frequency and class width

B.Lower and upper limits

C.Median class and modal class

D.Mean and class mark