The reason is that your friend is having better content (at least in terms of ad generation) and thats why ads that have more pay per click value are appearing on his site. You should optimize your site's content so that better paying ads appear on your site.
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Sleight of hand and twist of fate...
On a bed of nails she makes me wait...
And I wait without you ...
With or without you ..
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Batty = Too Busy Now !!!
My friend earned 15$ for 350 Page impressions and 35 clicks
and mine is 450 Page impressions and 50 clicks
and my earning is 0.71$
Can any one tell me what is the reason???
He may have Targeted traffic, the traffic on your page is didn't click on Adsense ad put there as the ads are not Attrecting Them. Try to change title of page and keep it related to content of Page.