Proportional to sqrt ?? (1 Viewer)

[Nivek5]

http://www.boardofstudies.nsw.edu.au/hsc_exams/hsc2008exams/pdf_doc/2008HSC-general-mathematics.pdf Question 19 of multi choice. I dont understand how to get the answer of B I can work it out through trial and error going through the possible answers.. but its not eh correct way. can someone help me???

 

[PC]

h is proportional to √n
.: h = k x √n , where k is the constant of proportionality

When h = 35, n = 2000
.: 35 = k x √2000
k = 35/√2000

So put this in our formula.
h = 35/√2000 x √n

Now, when n = 10000:
h = 35/√2000 x √10000
= 78.26237921
= 78 cm

 

[Nivek5]

ahhhh thats better

I was using 10,000 instead of √10000 in the last step.

Thank you