A student scores the following marks in 5 subjects: 60, 75, 80, 90, 95. What is the standard deviation?
Solution:
Step 1: Find the mean Mean = (60 + 75 + 80 + 90 + 95) ÷ 5 = 400 ÷ 5 = 80
Step 2: Find deviations from mean and their squares
Marks | Deviation (x − 80) | Square |
60 | −20 | 400 |
75 | −5 | 25 |
80 | 0 | 0 |
90 | +10 | 100 |
95 | +15 | 225 |
Sum of squares = 400 + 25 + 0 + 100 + 225 = 750
Step 3: Variance Variance = 750 ÷ 5 = 150
Step 4: Standard deviation SD = √150 ≈ 12.25
Nearest option = 12.5
Correct Answer: (c)
English
30 Questions
30 Marks
27 Mins English English100 Questions100 Marks120 Mins English English75 Questions300 Marks90 Mins EnglishIf mean of the following distribution is 211, then what is the value of (4p – 3q)?
If x and y are upper limit of median class and lower limit of modal class, respectively in the following distribution, then what is the value of (2x + y)?
The following is the distribution of ages (in years) of children in a group:
What is the median age (in years) of children ?
If the mode of the following distribution is , then what is the value of k?
The median of the observations 6, 48, 32, 3, 37 and 18 is:
A student scores the following marks in 5 subjects: 60, 75, 80, 90, 95. What is the standard deviation?
The marks scored by 10 students are given below. 13, 20, 15, 13, 19, 12, 12, 11, 13, 10 The mode of the given data is:
In the following frequency distribution
| Height (in cm) | 140–145 | 145–150 | 150–155 | 155–160 | 160–165 | 165–170 |
| No. of students | 13 | 15 | 9 | 10 | 8 | 5 |
The sum of the upper limit of the modal class and the lower limit of the median class:
The median of a set of 9 distinct observations is 20.5. If each of the largest four observations of the set is increased by 2, then the median of the new set:
Suggested Test Series
Suggested Test Series
