fluke wrote:
siddhans wrote:
Fluke,
Looks like i got a fluke here
Just kidding ... So whats the fastest way of finding mean here?
Add them up and divide by 10. Should not take more than 15 secs.
70,75,80,85,90
80*5 =400
130*3=390
105*2=210
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1000
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Here is how I computed the mean. It was pretty fast, and did not involve too many calculations: 70 75 80 85 90 105 105 130 130 130
First term (70 (100-30)) and last term (130 (100+30)) : Mean is 100.
Second term (75 = 70 + 5= (100-30
+ 5)) and 9th term (130): Mean is 100. 5 is carried over later.
Third term (80 = 70 + 10 = (100-30
+ 10)) and 8th term (130): Mean is 100. 10 is carried over later.
Leave the fourth term (85) for the moment.
Take the fifth term (90) and add (5+10) from earlier to make a total of 105.
Then add this 105 with the remaining two 105 (6th and 7th terms), along with the fourth term to get:
Mean = \(\frac{(105*3+85)}{4}\) = 100.
Though the explanation is kind of long, the computation is faster than computing by addition and multiplication of all terms.