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if the hight of a cylinder is 4 inches, and the volume is 15 ml, whats the diameter?

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2 Answers

V=(∏D2/4)*h
Plugging all the data in the above formula, we obtain:
15=(∏D2/4)*4*2.54
D2= 1.90 cm
D= 1.38 cm
D= 0.54 inches
For 10 ml D2will be 1.2666
D will be 1.1254 cm and
D= 0.443 inches
for the 20Ml D2 = 2.532

Comments

I made a big mistake because I though that the volume was given in inches3, I already fixed it, thanks to the tutor.
no worries man! your awesome!

what would be the answer if the ml was 10, and 20??
Zack,
 
1st of all we need to get everything into a consist system of units.  For the volume V = 15 mL,
one mL = 1 cm , so rather than try to convert this to cubic inches lets work with cm since the conversion from inches to cm is straight forward.  1 inch = 2.54 cm, so 4 inches x 2.54 cm per inch = 10.16 cm.
 
Now for a cylinder, volume = height (h) x area of the base (pi*radius squared).
 
so V = h*pi*r²
 
To find r we rearrange:  r² = V/(h*pi) , so r = [V/(h*pi)]½ 
 
and d = 2*r
 
Solving for r we get r = [15 cm 3 /(10.16 cm * 3.14)] ½ = 0.69 cm
 
then d = 2*r =1.4 cm
 
Let's check our result.  V = h*pi*r² , so V = 10.16 cm * pi * (0.69 cm)² = 15.2 cm³ ,
 
so we're right back where we started within round off errors.
 
Now if you like you can convert d = 1.4 cm back to inches :  1.4 cm / 2.54 cm per inch = 0.55 inches
 

Comments

Thanks a lot. your awesome! 
 
what would be the answer if the ml was 10, and 20??