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Rates of Change, SMB-005

Fuifui finds that for Giant moray eels, the mass of an eel `(M)` is directly proportional to the cube of its length `(l)`.

An eel of this species has a length of 15 cm and a mass of 675 grams.

What is the expected length of a Giant moray eel with a mass of 3.125 kg? Give your answer to one decimal place.  (3 marks)

--- 6 WORK AREA LINES (style=lined) ---

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`25\ text{cm}`

Show Worked Solution

`M prop l^3`

`M = kl^3`
 

`text(Find)\ k:`

`675` `= k xx 15^3`
`k` `= 675/15^3`
  `= 0.2`

 
`text(Find)\ \ l\ \ text(when)\ \ M = 3125:`

`3125` `= 0.2 xx l^3`
`l^3` `= 3125/0.2`
`:. l` `= root3(15\ 625)`
  `= 25\ text{cm}`

Filed Under: Variation and Rates of Change Tagged With: num-title-ct-patha, smc-4239-40-a prop other

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