smc-6923-20-Identify Graph

Algebra, STD2 A4 2004 HSC 21 MC

The time `(t)` taken to clean a house varies inversely with the number `(n)` of people
cleaning the house.

Which graph represents this relationship?

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`D`

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`t \prop 1/n \ \ =>\ \ t = k/n`

`text(The graph is a hyperbola that sees)\ t\ text(decrease as)\ n\ text{increases (eliminate A and B).}`

`text(Also,)\ t\ text{cannot be zero (eliminate C).}`

`=> D`

The time for a car to travel a certain distance varies inversely with its speed.

Which of the following graphs shows this relationship?

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`A`

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`T prop 1/S\ \ =>\ \ T=k/S`

`text{By elimination:}`

`text(As S) uarr text(, T) darr => text(cannot be B or D)`

♦ Mean mark 38%

`text(C is incorrect because it graphs a linear relationship.)`

`=> A`