4400 Higher November 2010 Paper 4 Q16

EdexcelHigherOld spec5 marksDirect & Inverse Proportion

16 \(P\) is inversely proportional to \(V\).
\(P = 18\) when \(V = 24\)

(a) Express \(P\) in terms of \(V\). (3)

(b) Find the positive value of \(V\) when \(P = 3V\) (2)

Mark scheme (a)

Scheme	Marks
\(P = \dfrac{k}{V}\)	M1
\(18 = \dfrac{k}{24}\)	M1
\(P = \dfrac{432}{V}\)	A1
	(3)

Notes

M1: for \(P = \dfrac{k}{V}\) but not for \(P = \dfrac{1}{V}\)

Also award for a correct equation in \(P\), \(V\) and a constant

or \(P\) = some numerical value \(\times \dfrac{1}{V}\)

M1: for \(18 = \dfrac{k}{24}\) or for correct substitution into an equation which scores first method mark (may be implied by correct evaluation of the constant)

A1: Award 3 marks if answer is \(P = \dfrac{k}{V}\) but \(k\) is evaluated as 432 in any part

Scheme	Marks
\(3V^2 = 432\) or \(3V \times V = 432\)	M1
12	A1
	(2)
	(5 marks)