Time taken to solve a few questions by each student is given in the table who is the fastest of all

Given that the times (in seconds) taken to solve a problem by each of 25 pupils are 16, 20, 26, 27, 28, 30, 33, 37, 38, 40, 42, 43, 46, 46, 46, 48, 49, 50, 53, 58, 59, 60, 64, 52 and 20. The minimum and maximum time values are 16 and 64 respectively.

(a) At first construct the following frequency distribution for the given data. Since, the lowest value is 16; we start with the class-interval 15-25, as the class size must be 10.

Class - Intervals  Tally Frequency
15-25 lll 3
25-35 lllll 5
35-45 lllll 5
45-55 llllllll 8
55-65 llll 4

(b) To represent the given data by a histogram, we first draw horizontal and vertical axes. Let us consider that the horizontal and vertical axes represent the class-limits and the frequencies of the class-intervals respectively.

The above data is a continuous grouped frequency distribution with equal class-intervals, which is 10. Construct rectangles with class-intervals as bases and respective frequencies as heights.

The histogram of the data in part (a) is as follows: 

Time taken to solve a few questions by each student is given in the table who is the fastest of all

Time taken to solve a few questions by each student is given in the table who is the fastest of all

Free

15 Questions 15 Marks 18 Mins

Given

10 questions solve in 5 minutes by one student

20 questions solve by second student in 10 minutes

Concept: 

Use unitary method

First find the time to solve one question by each of the student.
 

Calculation

First student solve question in 1 minute = 10/5

= 2 questions

Second student solve question in 1 minute = 20/5

= 4 questions

Number of questions solve in 1 minute by both the students together

= 2 + 4 = 6

300 question solve in 50 minutes [(i.e. 300 × (1/6)]

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Q. The time taken, in seconds, to solve a problem by each of 25 pupils is as follows: 16, 20, 26, 27, 28, 30, 33, 37, 38, 40, 42, 43, 46, 46, 46, 48, 49, 50, 53, 58, 59, 60, 64, 52, 20 (a) Construct a frequency distribution for these data, using a class interval of 10 seconds.

(b) Draw a histogram to represent the frequency distribution.