Plz Solve this math question for me...

[rickyponting66]

Q.      The Volume if two spheres are 640cm3  and  270cm3 .  Find the ratio of their diameters?



This is a question from "Area and Volume" and in most of this type of questions this formulae is used   "v1/v2=(L1/L2)`3"...

Help Plz..

[Ghost Of Highbury]

okk..first find the diameter of the biger sphere

4/3 pi * r^3 = 640

r^3 = 640/4.18

r = cube root of (152.78) = 5.34

so diameter = 2 * 5.34 = 10.68

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same for the smaller one..

4/3 pi r^3 = 240

r^3 = 240/4.188 = 57.29

r = 3.85

so diameter= 2 * 3.85 = 7.7


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so the ratio = 10.68 / 7.7 = 1.3

[rickyponting66]

Your Answer is Wrong...
Its answer is 4:3 .  But How?

[Ghost Of Highbury]

its correct...1.3 can be expressed as 4:3

[Ghost Of Highbury]

1.3:1 multiply both by 3 ==> which gives u . 4:3

[nid404]

that's right

[Ghost Of Highbury]

told him so..

[rickyponting66]

but why would I multiply ratio with 3?

[nid404]

but why would I multiply ratio with 3?

to remove the decimal....ratios are in whole numbers preferably

[rickyponting66]

I am still confused

[nid404]

the ratios are 1.3:1....to remove the decimal point and make it a whole number you multiply it with the number which would result in a number closest to a whole number.....so that number is 3.
it gives u 3.99(1.3X3)....very close to four...and 1X3=3
hence ratio is 4:3

remember you are not changing the ratio....

[nid404]

I have answered some questions you had posted earlier...tell me if they r right or not