(a) Find the smallest integer that satisfies the inequality \(x + 8 < 4x -

MATHEMATICS
WAEC 2005

(a) Find the smallest integer that satisfies the inequality \(x + 8 < 4x - 15\).

(b) A sales girl is paid a monthly salary of N2,500 in addition to a commission of 5 kobo in the naira on all sales made by her during the month. If her sales for a month amounts to N200,000.00, calculate her income for that month.

(c)rectangle and semi-circle shape The diagram shows a window consisting of a rectangular and semi- circular parts. The radius of the semi- circular part is 35 cm and the height of the rectangular part is 50 cm. Find the area of the window. [Take \(\pi = \frac{22}{7}\)].

Explanation

(a) \(x + 8 < 4x - 15 \implies 4x - 15 > x + 8\)

\(4x - x > 8 + 15 \implies 3x > 23\)

\(x > \frac{23}{3}\)

\(x > 7\frac{2}{3}\).

(b) Extra income = 5k of N200,000

= \(\frac{5}{100} \times N200,000\)

= \(N10,000\)

Total income = Monthly income + commission

= N(2,500 + 10,000)

= N12,500.

(c) Area of semi- circle = \(\frac{\pi r^{2}}{2}\)

= \(\frac{1}{2} \times \frac{22}{7} \times 35 \times 35\)

= \(1925 cm^{2}\)

Length of rectangular part = 50 cm

Breadth = Diameter of semi- circle = 2(35 cm) = 70 cm

Area of rectangular part = \(length \times \breadth\)

= \(50 \times 70\)

= \(3500 cm^{2}\)

Total area of window = \((3500 + 1925) cm^{2}\)

= \(5425 cm^{2}\)

(a) \(x + 8 < 4x - 15 \implies 4x - 15 > x + 8\)

\(4x - x > 8 + 15 \implies 3x > 23\)

\(x > \frac{23}{3}\)

\(x > 7\frac{2}{3}\).

(b) Extra income = 5k of N200,000

= \(\frac{5}{100} \times N200,000\)

= \(N10,000\)

Total income = Monthly income + commission

= N(2,500 + 10,000)

= N12,500.

(c) Area of semi- circle = \(\frac{\pi r^{2}}{2}\)

= \(\frac{1}{2} \times \frac{22}{7} \times 35 \times 35\)

= \(1925 cm^{2}\)

Length of rectangular part = 50 cm

Breadth = Diameter of semi- circle = 2(35 cm) = 70 cm

Area of rectangular part = \(length \times \breadth\)

= \(50 \times 70\)

= \(3500 cm^{2}\)

Total area of window = \((3500 + 1925) cm^{2}\)

= \(5425 cm^{2}\)



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