4400 Higher June 2008 Paper 4 Q20

EdexcelHigherOld spec5 marksStandard Form

(a) Evaluate \(5 \times 10^{12} + 9 \times 10^{12}\)
Give your answer in standard form. (2)

(b) Each of the numbers \(p\), \(q\) and \(r\) is greater than 1 and less than 10
\(p \times 10^{15} + q \times 10^{15} = r \times 10^n\)
\(p + q \gt 10\)

(i) Find the value of \(n\).

(ii) Find an expression for \(r\) in terms of \(p\) and \(q\).

(3)

Scheme	Marks
\(14 \times 10^{12}\) oe	M1
\(1.4 \times 10^{13}\)	A1
	(2)

Mark scheme (b)

Scheme	Marks
(i) Answer: 16	B1
(ii) \((p + q) \times 10^{15} = r \times 10^n\)	M1
\((p + q)/10\) oe	A1
	(3)
	(5 marks)

Notes

B1: cao

M1: may be seen in (i)

A1: \(0.1(p + q)\), \((p + q) \times 10^{-1}\), \(\dfrac{p \times 10^{15} + q \times 10^{15}}{10^{16}}\)