Math Is Fun Forum

lemonz

Member

Registered: 2009-01-16

Posts: 1

re: median problem - statistics

Hi:

A nuber of cats are weighed:
30% weigh 2 kg or less
80% weigh 5 kg or less
Estimate the median cat weight

can anybody give an answer, please?
thank you

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: re: median problem - statistics

You need to assume that of all the cats that weigh between 2 and 5 kg, their weights are uniformly distributed.

ie. The number of cats that weigh 3kg is the same as the number that weigh 4kg, which is also the number that weight 2.5kg, etc.

From here, you just look at what position 50% is at in relation to 30% and 80%, and estimate the median weight according to the same ratio.

On the line between 30 and 80, 50 is 2/5s along from 30.
So then the median weight should be 2/5s along from 2kg, on the line between 2 and 5.

This works out to be 3.2kg.

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Why did the vector cross the road?
It wanted to be normal.