A sequence is given by 2 frac 1 2 5 7 frac 1 2 ... - WAEC Mathematics 2005 Question
A sequence is given by \(2\frac{1}{2}, 5, 7\frac{1}{2}, .....\) if the nth term is 25, find n
A
9
B
10
C
12
D
15
correct option: b
\(a = 2\frac{1}{2}, nth = a + (n-1)d \Rightarrow 25 = 2\frac{1}{2} + (n-1)2\frac{1}{2}\
25 = \frac{5}{2}+(n-1)\frac{5}{2} \Rightarrow 22\frac{1}{2} = \frac{5n-5}{2}\Rightarrow \frac{45}{2} = \frac{5n-5}{2}\
45 = 5n - 5 \Rightarrow 5n = 50 \Rightarrow n = 10\)
25 = \frac{5}{2}+(n-1)\frac{5}{2} \Rightarrow 22\frac{1}{2} = \frac{5n-5}{2}\Rightarrow \frac{45}{2} = \frac{5n-5}{2}\
45 = 5n - 5 \Rightarrow 5n = 50 \Rightarrow n = 10\)
Please share this, thanks:
Add your answer
No responses