Three values of a variable are 4, 5 and 7, if their frequencies are p – 2, p + 1 and p – 1 respectively and the Mean is 5.4, then the value of p is:
WBBSE
Class X
Mathematics
Statistics
01 Mark
2023
(d) 4
Explanation
Mean = \frac{∑\text{fx}}{∑\text{f}}
or, 5.4 = \frac{4(p - 2) + 5(p + 1) + 7(p - 1)}{(p - 2) + (p + 1) + (p - 1)}
or, 5.4 = \frac{\text{6p - 10}}{\text{3p - 2}}
or, 16p – 10 = 5.4 (3p – 2)
or, 16p – 16.2p = -10.8 + 10
or, 0.2p = 0.8
or, p = 4
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