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2015 WAEC Mathematics Theory (a) The first term of an Arithmetic Progression (AP) is 8, the ratio of the...

Mathematics
WAEC 2015

(a) The first term of an Arithmetic Progression (AP) is 8, the ratio of the 7th term to the 9th term is 5 : 8, find the common difference of the AP.

(b) A trader bought 30 baskets of pawpaw and 100 baskets of mangoes for N2,450.00. She sold the pawpaw at a profit of 40% and the mangoes at a profit of 30%. If her profit on the entire transaction was N855.00, find the (i) cost price of a basket of pawpaw ; (ii) selling price of the 100 baskets of mangoes.

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Explanation

(a) \(T_{1} = a = -8\)

\(\frac{T_{7}}{T_{9}} = \frac{5}{8}\)

\(\frac{a + 6d}{a + 8d} = \frac{5}{8} \implies \frac{-8 + 6d}{-8 + 8d} = \frac{5}{8}\)

\(-8 + 6d = \frac{5}{8}(-8 + 8d) \implies -8 + 6d = -5 + 5d\)

\(6d - 5d = -5 + 8\)

\(d = 3\)

(b) Let :

the cost price \(CP_{1}\) of a basket of pawpaw be w;

the cost price \(CP_{2}\) of a basket of mangoes be m.

Then \(30w + 100m = N2,450 ..... (1)\)

Also, let :

The selling price of the baskets of pawpaw be \(SP_{1}\);

the selling price of the baskets of mangoes be \(SP_{2}\).

Then \(SP_{1} + SP_{2} = N(2,450 + 855) = N3,305 ...... (2)\)

%age profit on the sale of pawpaw = \(\frac{SP_{1} - CP_{1}}{CP_{1}} \times 100%\)

i.e. \(40% = \frac{SP_{1} - 30w}{30w} \times 100%\)

\(\implies 40 \times 3w = (SP_{1} - 30w) \times 10\)

\(12w = SP_{1} - 30w\)

\(SP_{1} = 12w + 30w = 42w\)

%age profit on the sale of mangoes = \(\frac{SP_{2} - CP_{2}}{CP_{2}} \times 100%\)

i.e. \(30% = \frac{SP_{2} - 100m}{100m} \times 100%\)

\(\implies 30m = SP_{2} - 100m\)

\(SP_{2} = 30m + 100m = 130m\)

But \(SP_{1} + SP_{2} = N3,305\)

\(\implies 42w + 130m = 3305 .... (2)\)

From (1), \(m = \frac{2450 - 30w}{100}\)

\(m = \frac{245 - 3w}{10}\)

Substitute \(m = \frac{245 - 3w}{10}\) in (3)

\(42w + 130(\frac{245 - 3w}{10}) = 3305\)

\(42w + 3,185 - 39w = 3305\)

\(3w = 3305 - 3185 = 120\)

\(w = N40.00\)

(i) Hence, the cost price of a basket of pawpaw = N40.00.

(ii) From (2),

\(SP_{1} + SP_{2} = 3305\)

\(42w + 130m = 3305 \implies 42 \times 40 + 130m = 3305\)

\(1680 + 130m = 3305\)

\(130m = SP_{2} = 3305 - 1680\)

= \(N1,625.00\) 

Hence, the selling point of 100 baskets of mangoes = N1,625.00.


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WAEC offline past questions - with all answers and explanations in one app - Download for free
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
WAEC Past Questions, Objective & Theory, Study 100% offline, Download app now - 24709
WAEC May/June 2024 - Practice for Objective & Theory - From 1988 till date, download app now - 99995
WAEC offline past questions - with all answers and explanations in one app - Download for free
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts