100m RACE A stopwatch was used to find the time that it took a group of students to run 100 m. Time (in sec) 0-20 20 - 40 40 -60 60 -80 80 -100 No. of students 8 10 13 6 3 a. Estimate the mean time taken by a student to finish the race. (i)54 (ii)63 (iii)43 (iv)50 b. What wiil be the upper limit of the modal class ? (i)20 (ii)40 (iii)60 (iv)80 c. The construction of cumulative frequency table is useful in determining the (i)Mean (ii)Median (iii)Mode (iv)All of the above d. The sum of lower limits of median class and modal class is (i)60 (ii)100 (iii)80 (iv)140 e. How many students finished the race within 1 minute? (i)18 (ii)37 (iii)31 (iv)8
Answers
Given : A stopwatch was used to find the time that it took a group of students to run 100 m.
Time (in sec) 0-20 20-40 40-60 60-80 80-100
No. of students 8 10 13 6 3
To Find : How many students finished the race within 1 minute?
(i)18
(ii)37
(iii)31
(iv)8
Solution:
Time (in sec) f cf
0-20 8 8
20-40 10 18
40-60 13 31
60-80 6 37
80-100 3 40
1 minute = 60 sec
Time less than 60 sec = 31 Students
31 students finished the race within 1 minute
option iii) is correct
mean time taken by a student to finish the race = (10*8 + 30*10+50*13+70*6+90*3)/40
= (8 + 30 + 65 + 42 + 27)/4
= 172/4
= 43 secs
40-60 is modal class hence upper limit of modal class = 60
The construction of cumulative frequency table is useful in determining the Median
Modal class and median class = 40 - 60
The sum of lower limits of median class and modal class is
40 + 40 = 80
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- Step-by-step explanation:
- 43
- 60
- median
- 8o
you got your answer all ready