Q.1 The mean of five numbers is 12. If one of the numbers is 20, what is the mean of the remaining four numbers?
11
10
9
12
Explanation - The total sum of five numbers = 5 × 12 = 60. Remaining sum = 60 - 20 = 40. Mean of remaining four numbers = 40 / 4 = 10.
Correct answer is: 10
Q.2 In a normal distribution, approximately what percentage of data lies within one standard deviation from the mean?
50%
68%
95%
99.7%
Explanation - In a normal distribution, 68% of data falls within ±1 standard deviation, 95% within ±2, and 99.7% within ±3.
Correct answer is: 68%
Q.3 If the variance of a dataset is 16, what is the standard deviation?
2
4
8
16
Explanation - Standard deviation is the square root of variance. √16 = 4.
Correct answer is: 4
Q.4 A researcher records the blood pressure of 100 patients. The middle value of the readings is known as:
Mean
Median
Mode
Range
Explanation - Median is the middle value of a dataset when arranged in order.
Correct answer is: Median
Q.5 If the probability of an event A is 0.7, what is the probability of A not occurring?
0.3
0.7
1.0
0.0
Explanation - Probability of not A = 1 - P(A) = 1 - 0.7 = 0.3.
Correct answer is: 0.3
Q.6 Which measure of central tendency is most affected by extreme values?
Mean
Median
Mode
All equally affected
Explanation - Mean is sensitive to extreme values, whereas median and mode are more robust.
Correct answer is: Mean
Q.7 The range of the dataset {5, 8, 12, 20, 25} is:
20
25
12
5
Explanation - Range = Maximum - Minimum = 25 - 5 = 20.
Correct answer is: 20
Q.8 Which type of graph is best suited for representing proportions of a whole?
Histogram
Bar chart
Pie chart
Line graph
Explanation - Pie charts visually represent parts of a whole, showing percentages or proportions.
Correct answer is: Pie chart
Q.9 A dataset has an interquartile range (IQR) of 20. What does IQR represent?
Difference between max and min
Difference between Q3 and Q1
Average of all values
Variance of the dataset
Explanation - IQR = Q3 - Q1, measures the spread of the middle 50% of the data.
Correct answer is: Difference between Q3 and Q1
Q.10 Which statistical test is commonly used to compare means of two independent groups?
Chi-square test
t-test
ANOVA
Correlation test
Explanation - The independent t-test compares the means of two independent groups to see if they differ significantly.
Correct answer is: t-test
Q.11 If 40% of patients in a study are male, what is the ratio of males to females?
2:3
3:2
4:6
6:4
Explanation - If 40% are male, then 60% are female. Ratio = 40:60 = 2:3.
Correct answer is: 2:3
Q.12 In a dataset, if the sum of deviations from the mean is calculated, the result is always:
Positive
Negative
Zero
Depends on data
Explanation - The sum of deviations from the mean is always zero by definition.
Correct answer is: Zero
Q.13 Which of the following is a measure of relative variability?
Standard deviation
Variance
Coefficient of variation
Range
Explanation - CV = (SD / Mean) × 100, gives a measure of variability relative to the mean.
Correct answer is: Coefficient of variation
Q.14 The mode of the dataset {4, 4, 6, 6, 6, 8, 9} is:
4
6
8
9
Explanation - Mode is the value that occurs most frequently. 6 occurs 3 times.
Correct answer is: 6
Q.15 Which of the following best describes a positive skewed distribution?
Mean < Median
Mean > Median
Mean = Median
Median > Mode
Explanation - In a positively skewed distribution, the tail is on the right, pulling the mean above the median.
Correct answer is: Mean > Median
Q.16 A dataset has a mean of 50 and a standard deviation of 5. A value of 60 corresponds to how many standard deviations from the mean?
1
2
3
4
Explanation - Number of SDs = (Value - Mean) / SD = (60 - 50)/5 = 2.
Correct answer is: 2
Q.17 If the probability of a disease in a population is 0.1, what are the odds of having the disease?
0.1
0.11
1:9
9:1
Explanation - Odds = P / (1 - P) = 0.1 / 0.9 = 1/9.
Correct answer is: 1:9
Q.18 Which diagram is most appropriate to show frequency distribution of a continuous variable?
Histogram
Bar chart
Pie chart
Scatter plot
Explanation - Histogram is used to display frequency distribution of continuous variables.
Correct answer is: Histogram
Q.19 A study reports a relative risk of 1. What does this indicate?
No association
High risk
Low risk
Cannot be determined
Explanation - Relative risk of 1 indicates no difference in risk between exposed and unexposed groups.
Correct answer is: No association
Q.20 Which measure of central tendency divides a dataset into four equal parts?
Quartiles
Deciles
Percentiles
Median
Explanation - Quartiles divide data into four equal parts: Q1, Q2 (median), Q3.
Correct answer is: Quartiles
Q.21 A researcher wants to study the relationship between height and weight. Which statistical method is most appropriate?
Correlation
Chi-square test
t-test
ANOVA
Explanation - Correlation measures the strength and direction of a linear relationship between two continuous variables.
Correct answer is: Correlation
Q.22 If the coefficient of variation (CV) of dataset A is 10% and of dataset B is 20%, which dataset is more variable?
A
B
Both same
Cannot determine
Explanation - Higher CV indicates greater relative variability.
Correct answer is: B
Q.23 Which type of data can be represented by a scatter plot?
Categorical
Ordinal
Continuous
Nominal
Explanation - Scatter plots show the relationship between two continuous variables.
Correct answer is: Continuous
Q.24 If 25 students scored 80 in an exam, and 25 scored 90, what is the median score?
80
85
90
Cannot determine
Explanation - Median is the middle value. Ordered scores: 25×80, 25×90. Middle value between 80 and 90 = 85.
Correct answer is: 85