Page 262 - ICSE Math 7

(d) If each observation is increased by 1, then the value of the mean for new data ___________.

(i) increases by 1 (ii) decreases by 1
(iii) remains the same (iv) can’t be determined

(e) A shopkeeper keeps a weekly record of sales of different sizes of shirts. The central tendency
which cannot be ignored while placing an order for procurement of shirts is ___________.
(i) mean (ii) median

(iii) mode (iv) range
2. Write True or False.

(a) The value of the arithmetic mean is not affected by extreme values.
(b) Median of raw data is not affected by extreme values.

(c) Mean is always one of the observations in the data.
(d) Median is one of the observations in the data if the number of observations are odd.

(e) The value of mean, median and mode can never be equal.
(f) The value of mean always lies between the minimum and maximum value of the data.

3. Fill in the blanks.
(a) In the data, the numbers 1, 2 and 3 repeat as many times as their value. The mode and median
of the observations are ___________ and ___________ respectively.

(b) The ___________ divides a data into two equal halves.
(c) The mode of series of 7 observations is 50. If by mistake the whole series is repeated once
again, then the mode of 14 observations so obtained is ___________.
(d) Krish scored 100 out of 100 marks in his final Mathematics examination. The range of the
marks scored by the class is 40. The lowest marks scored in the class are ___________.

(e) Tally marks are used to evaluate ___________.
(f) The arithmetic mean of the first 99 natural numbers is ___________.

PRACTICE TIME

1. Find the median of the first:
(a) hundred whole numbers
(b) hundred natural numbers

(c) twenty-five odd numbers

2. The average age of a group of 7 athletes is 22 years. An athlete whose age is 36 years joins the
group. Will the average age of the group increase or decrease? Find out by how much?

3. The average of 3 different numbers is 17. Two of the numbers are 8 and 12. Find the third
number.
4. Name the measure of central tendency associated with each phrase.

(a) middle (b) most often (c) average

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