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How do you find the mode from a CDF ?

Without sketching the graph.
differentiate to pdf and differentiate to find turning point
Original post by nisha.sri
Without sketching the graph.


Differentiate to get the probability density function, and then we want the highest point on that curve, so you'll need to differentiate again and set the derivative of the PDF equal to 0 to find the x-value.
Original post by Prasiortle
Differentiate to get the probability density function, and then we want the highest point on that curve, so you'll need to differentiate again and set the derivative of the PDF equal to 0 to find the x-value.


Ok so the pdf is 9x/10 -- 3x^2/10 so then you would have to differentiate that again to get 9/10 - 3x/20 and equal it to 0 ? Is that right :colondollar:
Original post by nisha.sri
Ok so the pdf is 9x/10 -- 3x^2/10 so then you would have to differentiate that again to get 9/10 - 3x/20 and equal it to 0 ? Is that right :colondollar:


Your basic method is correct, but the derivative of 3x210\frac{3x^2}{10} is 3x5\frac{3x}{5}, not 3x20\frac{3x}{20}.
(edited 5 years ago)
Original post by Prasiortle
Your basic method is correct, but the derivative of 3x210\frac{3x^2}{10} is 3x5\frac{3x}{5}, not 3x20\frac{3x}{20}.


Oh yh yh ok thank you haha

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