JAMB Mathematics 2021 Objective — Question 2

Question 2 of 40 from the Joint Admissions and Matriculation Board (JAMB) Mathematics 2021 Objective paper, with the correct answer and a full explanation.

2. An A.P has 14 as its second term and 38 as its fifth term. Its tenth term and the sum of its first five terms are respectively (a) 75,110 (b) 65,124 (c) 110,78 (d) 141,33

A. 75,110
B. 65,124
C. 110,78Correct
D. 141,33

Explanation

Tn = a + (n-1)d. T2 = a+d = 14, T5 = a+4d = 38. Subtracting: 3d = 24, d = 8, a = 6. T10 = a+9d = 6+72 = 78. S5 = 5/2[2(6)+4(8)] = 5/2(44) = 110. So the tenth term (78) and sum of first five terms (110) match option (c).

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