Lesson 1: Variations

What does the letter 'k' stand for in the context of variation?

• constant of variation

• coefficient of variation

• variable of variation

• rate of change

One of the most important and useful ideas in Mathematics is the idea that two variables may be related to each other in such a way that, if one of the quantities increases or decreases the other quantity also increases or decreases in a definite way. What is this concept called?

• Variation

• Equation

• Constant

• Function

If y varies directly with x and y = 20 when x = 8, find the equation that relates x and y.

• y = 2.5x

• y = 8x

• y = 20x

• y = x + 20

If y varies inversely as x, and x = 5 when y = 2, find the equation that relates x and y.

• y = 10/x

• y = 2x

• y = x/10

• y = 5/x

If y varies inversely as x and y = 10 when x = 2, find y when x = 10.

• 2

• 5

• 1

• 20

It takes 8 days for 45 students to answer Grade 9 modules, how long will 40 students take to answer the same module?

• 9 days

• 7 days

• 8 days

• 10 days

V varies jointly as q and r. Write the equation that represents this relationship.

• V = kqr

• V = kq + r

• V = k + qr

• V = kq/r

If z is jointly proportional to x and y and z=6, when x=3 and y=4, find z when x=7 and y=2.

• 7

• 8

• 6

• 9

Write an equation for the following statement: The cost of fish F varies directly as its weight w in kilograms.

• F = kw

• F = k + w

• F = k/w

• F = w/k

The volume of a cylinder V varies jointly as its height h and the square of the radius r.

• V = khr