If the mean of the following data is $18.75$ . Find the value of $p$ .
$x_{i}$ : $10$ $15$ $p$ $25$ $30$
$f_{i}$ : $5$ $10$ $7$ $8$ $2$

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Solution

Mean = $\frac{\sum x_{i} f_{i}}{\sum f_{i}}$

$\Rightarrow$ mean = $\frac{(10 \times 5) + (15 \times 10) + (p \times 7) + (25 \times 8) + (30 \times 2)}{5 + 10 + 7 + 8 + 2}$

$\Rightarrow$ mean = $\frac{50 + 150 + 7 p + 200 + 60}{5 + 10 + 7 + 8 + 2} = 18.75$

$\Rightarrow 460 + 7 p = 600$

$\Rightarrow 7 p = 140$

$\Rightarrow p = 20$

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Similar questions

18.75

p

Class mark $(x_{i})$	$10$	$15$	$p$	$25$	$30$
Frequency $(f_{i})$	$5$	$10$	$7$	$8$	$2$

If the mean of the following data is 18.75, then the value of P is

$x_{i}$	10	15	20	25	30
$f_{i}$	6	8	p	10	6

\begin{matrix} x_{i} & 10 & 15 & p & 25 & 30 f_{i} & 5 & 10 & 7 & 8 & 2 \end{matrix}

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