The following table gives the life times of 400 neon lamps:

(i) Represent the given information with the help of a histogram.
(ii) How many lamps have a life time of more than 700 hours?

Solution:

(i) From the data given we plot the histogram as:

1. Represent the lifetime (in hours) in x-axis.
2. Represent the number of lamps in y-axis.
3. Class intervals are from 300-400 till 900-1000
4. Take “1 unit = 10 lamps” on y–axis as the lowest value of frequency is 14 and the highest is 86.
5. Also, since the first interval is starting from 300 and not ‘0’, we show it by marking a ‘kink’ or a break on the x-axis.

It can be seen from the above graph that:

(ii) The number of neon lamps having their lifetime of more than 700 hours lies in the class intervals 700 – 800, 800 – 900, 900 – 1000.

Hence, their corresponding frequencies when added up will be (74 + 62 + 48) = 184 lamps.

☛ Check: NCERT Solutions for Class 9 Maths Chapter 14

Video Solution:

The following table gives the lifetimes of 400 neon lamps: i) Represent the given information with the help of a histogram. (ii) How many lamps have a lifetime of more than 700 hours?

NCERT Solutions for Class 9 Maths Chapter 14 Exercise 14.3 Question 5

Summary:

The data of lifetimes of 400 neon lamps is given. We have found that number of neon lamps having their lifetime of more than 700 hours lies in the class intervals “700 – 800, 800 – 900, 900 – 1000”. Hence, their corresponding frequencies when added up will be (74 + 62 + 48) = 184 lamps.

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