Class X Statistics Exercise 14.2

Class X

Statistics Exercise 14.2

QUESTION 1.    The following table shows the ages of the patients admitted in a hospital during a year:
Sol. Mode:
          Here, the highest frequency is 23.
          The frequency 23 corresponds to the class interval 35 – 45.
         The modeal class is 35 – 45
         Now, Class size (h) = 10
         Lower limit (l) = 35
         Frequency of the modal class (f1) = 23
         Frequency of the class preceding the modal class
                 f0 = 21
         Frequency of the class succeeding the modal class
                 f2 = 14
         Mode = 
         
         
         
         
         = 36.8 years (approx.)
         Mean
         Let assumed mean a = 40
          h = 10
          
          
          
           Required mean = 35.37 years.

Class X Statistics Exercise 14.2

QUESTION 2.    The following data gives the information on the observed lifetimes (in hours) of 225 electrical components:
Determine the modal lifetimes of the components.
Sol. Here, the highest frequency = 61.
          The frequency 61 corresponds to class 60 – 80
           The modal class = 60 – 80
           We have: l = 60
              h = 20
              f1 = 61
              f0 = 52
              f2 = 38
          Mode = 
          
          
          
          
          = 65.625 hours.
          Thus, the required modal life times of the components is 65.625 hours.

Class X Statistics Exercise 14.2

QUESTION 3.     The following data gives the distribution of total monthly household expenditure of 200 families of a village. Find the modal monthly ependiture of the families. Also, the mean monthly expenditure:
Sol.  Mode:
           The maximum number of families 40 have their total monthly expenditure is in interval 1500 – 2000.

           Modal class is 1500 – 2000.

              I = 1500,                       h = 500
              f1 = 40,                           f0 = 24
              f2 = 33
           Mode = 
          
          
          
          
          Thus, the required modal monthly expenditure of the families is Rs. 1847.83.
          Mean: Let assumed mean (a) = 3250
          h = 500
           We have the following table:
          
          
          
          = 2662.5
          Thus, the mean monthly expenditure = Rs. 2662.50.
QUESTION 4.     The following distribution gives the state-wise teacher-student ratio in higher secondary schools of India. Find the mode and mean of this data. Interpret the two measures.
Sol.  Mode:
           Since the class 30 – 35 has the greatest frequency and h = 5
           l = 30
           f1 = 10
           f0 = 9
           f2 = 3
          Mode = 
          
          
           = 30 + 0.625 = 30.6 (approx).
           Mean:
           Let the assumed mean (a) = 37.5
           Since, h = 5
          We have the following table:
          
          
          

Class X Statistics Exercise 14.2

QUESTION 5.     The given distribution shows the number of runs scored by some top batsmen of the world in one-day international cricket matches. Find the mode of the data.
Sol.  The class 4000–5000 has the highest frequency i.e., 18
            h = 1000
           l = 4000
           f1 = 18
           f0 = 4
           f2 = 9
           Now, Mode = 
          
          
           = 4000 + 608.695
           = 4608.7 (approx.)
           Thus, the required mode is 4608.7.
QUESTION 6.      A student noted the number of cars passing through a spot on a road for 100 periods each of 3 minutes and summarised it in the table given below. Find the mode of the data:
Sol.   The class 40 – 50 has the maximum frequency i.e., 20
           f1 = 20, f0 = 12, f2 = 11 and h = 10
           Also l = 40
           Mode = 
          
          
          
          = 40 + 4.7 = 44.7

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