Question

the mean of 30 no. is 45,if the mean of 29 no. is also 45,then the 30th no.

Answer 1

Hlw mate

First thing we need tio do is to put the data in increasing order. This is needed to calculate the median:

30,31,32,33,34,35,35,36,37,39

Now we can calculate the parameters of this set:

Mean:

¯x=30+31+32+33+34+35+35+36+37+3910=34210=34.2

Median

To calculate the median we need to take "middle" elements in an ordered set. If the set has an odd number of elements, then there is only one middle element, otherwise there are 2 such elements and median is the mean of those elements.

To find the middle elements we can cross out elements at both ends of the set until only 1 or 2 remain uncrossed:

30,31,32,33,34,35,35,36,37,39

30,31,32,33,34,35,35,36,37,39

30,31,32,33,34,35,35,36,37,39

30,31,32,33,34,35,35,36,37,39

There are 2 uncrossed elements, so their mean is the median: Me=34+352=692=34.5

Mode is the element which occurs the most times in the set. Here it is 35.

Range is the difference between the smallest and the largest element: 

Hope it helpful

Answer 2

$\huge\boxed{\texttt{\fcolorbox{Red}{aqua}{Hey Mate!!!}}}$

$<b><i><font face=Copper black size=4 color=blue>$ Here is your answer.
Mean = Sum of All Numbers/Total Numbers

Sum of All Numbers = Mean × Total Numbers

Sum of 30 Numbers = 45 × 30
= 1350

Sum of 29 Numbers = 29 × 45
= 1305

Therefore 30th Number is = 1350 - 1305
= 45

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