Exercise 14.4 Solutions
From Class X Mathematics textbook by the State Council of Educational Research and Training, Telangana, Hyderabad
Question 1
The following distribution gives the daily income of 50 workers of a factory.
| Daily income (in Rupees) | 250-300 | 300-350 | 350-400 | 400-450 | 450-500 |
|---|---|---|---|---|---|
| Number of workers | 12 | 14 | 8 | 6 | 10 |
Convert the distribution above to a less than type cumulative frequency distribution, and draw its ogive.
Solution:
Step 1: Convert to less than type cumulative frequency distribution:
| Daily income less than (in Rupees) | 300 | 350 | 400 | 450 | 500 |
|---|---|---|---|---|---|
| Cumulative frequency | 12 | 12+14=26 | 26+8=34 | 34+6=40 | 40+10=50 |
Question 2
During the medical check-up of 35 students of a class, their weights were recorded as follows:
| Weight (in kg) | Less than 38 | Less than 40 | Less than 42 | Less than 44 | Less than 46 | Less than 48 | Less than 50 | Less than 52 |
|---|---|---|---|---|---|---|---|---|
| Number of students | 0 | 3 | 5 | 9 | 14 | 28 | 32 | 35 |
Draw a less than type ogive for the given data. Hence obtain the median weight from the graph and verify the result by using the formula.
Solution:
Step 1: The data is already in less than type cumulative frequency form.
Step 2: Drawing the ogive:
Ogive (Less than type) for weights of students
Step 3: Finding median from the graph:
Total number of students (n) = 35
Median position = n/2 = 17.5
From the graph, the x-coordinate corresponding to y=17.5 is approximately 46.5 kg.
Step 4: Verifying using the formula:
The median class is 46-48 (since 17.5 falls in the cumulative frequency of 28)
Using the formula:
\[ \text{Median} = L + \left(\frac{\frac{n}{2} – cf}{f}\right) \times h \]
Where:
L = 46 (lower limit of median class)
cf = 14 (cumulative frequency before median class)
f = 14 (frequency of median class)
h = 2 (class width)
\[ \text{Median} = 46 + \left(\frac{17.5 – 14}{14}\right) \times 2 = 46 + \left(\frac{3.5}{14}\right) \times 2 = 46 + 0.5 = 46.5 \text{ kg} \]
This matches our graphical estimate.
Question 3
The following table gives production yield per hectare of wheat of 100 farms of a village.
| Production yield (Quintal/Hectare) | 50-55 | 55-60 | 60-65 | 65-70 | 70-75 | 75-80 |
|---|---|---|---|---|---|---|
| Number of farmers | 2 | 8 | 12 | 24 | 38 | 16 |
Change the distribution to a more than type distribution, and draw its ogive.
Solution:
Step 1: Convert to more than type cumulative frequency distribution:
| Production yield more than (Quintal/Hectare) | 50 | 55 | 60 | 65 | 70 | 75 |
|---|---|---|---|---|---|---|
| Cumulative frequency | 100 | 100-2=98 | 98-8=90 | 90-12=78 | 78-24=54 | 54-38=16 |
Step 2: Drawing the ogive (more than type):
Ogive (More than type) for production yield