If x:y = 5:2x:y=5:2 and y:z = 3:2y:z=3:2, what is the ratio of x:zx:z?

3 Answers
Mar 23, 2016

x/z= 15/4" " ->" " x:z=15:4xz=154 x:z=15:4

Explanation:

To solve this you need to adopt the fraction style of ratio presentation

x/y=5/2xy=52

y/z=3/2yz=32

Need x/zxz

Consider x/yxxy/z xy×yz

Write this as:

(x xx y)/(yxx z)x×yy×z

'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
As an example of what I am about to do consider 3xx23×2. You have the same result if you reverse these numbers.

So 3xx2=2xx3=63×2=2×3=6
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

So (x xx y)/(yxx z)" " =" "(x xx y)/(z xx y)" " =" " x/z xxy/y" " =" "x/zx×yy×z = x×yz×y = xz×yy = xz

color(white)(.).

=>x/z=" "x/y xxy/z" " =" " 5/2xx3/2" " =" " 15/4xz= xy×yz = 52×32 = 154

Nov 18, 2016

Alternative approach

x:z" "->" "x/z=15/4x:z xz=154

Explanation:

x/y=5/2xy=52 ..................................Equation(1)
y/z=3/2yz=32...................................Equation(2)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

From equation (2) y=3/2zy=32z

Consider equation(1)

Substitute for y giving

x/y=5/2 " "->" "x/(3/2z)=5/2xy=52 x32z=52

2/3 x/z=5/223xz=52

x/z=3/2xx5/2 = 15/4xz=32×52=154

Nov 18, 2016

x : z = 15:4x:z=15:4

Explanation:

Before you can compare all three values in one ratio,
make yy the same in both ratios:

x" ":" "y" ":" " zx : y : z

5" ":" "2" ":" " z5 : 2 : z
color(red)(15" ":" "6)" ":" " z15 : 6 : z

x" ":" "3" ":" " 2x : 3 : 2
x" ":" "color(red)(6" ":" " 4)x : 6 : 4
color(red)(15" ":" "6)" ":" " z15 : 6 : z

Now that we have yy the same in both ratios:

color(red)(15" ":" "6" ":" " 4)15 : 6 : 4

:. x : z = 15:4