Toshiba bought 100 hens for Rs 8000 and sold 20 of these at a gain of 5%. At what gain percent she must sell the remaining hens so as to gain 20% on the whole?

Toshiba bought one hen for = 80 each.
gain of 5% on 80 = (1.05×80) = 84 each
or (20×84) = 1680 total
she want a total of 20% gain on 8000 =
(1.2×8000) = 9600 total
she need to make 9600 - 1680 = 7920 total on the last 80 hens.
she originally paid (80×80) = 6400 for those hens.
= 1.2375


so she need 23.75% gain on the remaining hens


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