A summary of 40 values of $$$x$$$ gives the following information: $$\[ \Sigma(x-k)=520, \quad \Sigma(x-k)^{2}=9640, \]$$ where $$$k$$$ is a constant. Given that the mean of these 40 values of $$$x$$$ is 34 , find the value of $$$k$$$. .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... .................................................................................................................................................... ....................................................................................................................................................

Mathematics

IGCSE&ALevel

CAIE

Exam No：9709_w21_qp_51 Year：2021 Question No：2(a)

Answer:

${\left[\frac{\sum x}{40}-k=\frac{\sum(x-k)}{40}\right] }$
$\frac{40 \times 34}{40}-k=\frac{520}{40}$
$k[=34-13]=21$

Knowledge points:

5.1.5 calculate and use the mean and standard deviation of a set of data (including grouped data) either from the data itself or from given totals , and use such totals in solving problems which may involve up to two data sets.

Answer:

Knowledge points:

Solution:

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