Sponsor Area

Application Of Derivatives

Question
CBSEENMA12035525

Manufacturer can sell x items at a price of rupees open parentheses 5 minus straight x over 100 close parentheses space each. The cost price of x items is Rs. open parentheses straight x over 5 plus 500 close parentheses. Find the number of items he should sell to earn maximum profit. 

Solution
straight C space equals space straight x over 5 plus 500
space straight R space equals space open parentheses 5 minus straight x over 100 close parentheses space left parenthesis straight x right parenthesis space equals space 5 straight x minus straight x squared over 100
straight P space equals space straight R space minus space straight C space equals space 5 straight x minus straight x squared over 100 minus straight x over 5 minus 500
therefore space space space space straight P space equals space 24 over 5 straight x minus straight x squared over 100 minus 500
space space space space space dP over dx space equals space 24 over 5 minus straight x over 50
    dP over dx space equals 0 space space space space space rightwards double arrow space space space 24 over 5 minus straight x over 50 space equals space 0 space space space space space space rightwards double arrow space space space straight x over 50 space equals space 24 over 5
therefore space space space space space space space straight x space equals space 24 over 5 cross times 50 space equals space 240
space space space space fraction numerator straight d squared straight P over denominator dx squared end fraction space equals space minus 1 over 50
When space straight x space equals space 240 comma space space space space fraction numerator straight d squared straight P over denominator dx squared end fraction space equals space minus 1 over 50 less than 0
therefore space space space space straight P space is space maximum space when space straight x space equals space 240
therefore space space space space manufacturer space can space earn space maximum space profit comma space if space he space sells space 240 space mins. space