If x varies jointly as y and z, and x = 8 when y = 4 and z = 9, find z when x = 16 and y = 6

Solution:

Let k be a non- zero constant variation 

x varies jointly as y and z

x = k × y × z  --- (1)

x = 8 when y = 4 and z = 9

Substitute the values of x,y and z in the equation (1)

8 = k × 4 × 9 = 36 k

k = 8/ 36 = 4 / 9

The equation of variation is x = (4 / 9) × y × z

To find z when x = 16 and y = 6.

Substitute x = 16 and y = 6 in the equation of variation

16 = (4/ 9) × 6 × z

16 = (24/ 9) × z

z =16 × 9/ 24

= 144 / 24 = 6

z = 6

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If x varies jointly as y and z, and x = 8 when y = 4 and z = 9, find z when x = 16 and y = 6

Summary:

If x varies jointly as y and z, the value of z will be 6, when x = 16 and y = 6.