After the first term in a sequence of positive integers,
the ratio of each term to the term immediately
preceding it is 2 to 1. What is the ratio of the
8th term in this sequence to the 5th term?
(A) 6 to 1
(B) 8 to 5
(C) 8 to 1
(D) 64 to 1
(E) 256 to 1



Answer :

The correct option is (C) 8 to 1.

The ratio of the 8th term in the sequence to the 5th term is 8:1.

What is geometric sequence?

The geometric sequence is a number sequence in which each term following the first is found through multiplying the preceding one by a fixed non-zero value known as the common ratio r.

Now, according to the question;

The geometric sequence can be written as;

[tex]a_{n}=2 a_{n-1}[/tex]

Where, r = 2.

In G.P;

[tex]a_{n}=a_{1} r^{n-1}[/tex]

Where [tex]a_{n}[/tex] shows nth term of an G.P.

and [tex]\mathrm{a}_{1}[/tex] show the first term of the G.P.

To evaluate the ratio of the 8th term to the 5th term;

[tex]\begin{aligned}&a_{8}=a_{1} 2^{8-1} \\&a_{8}=2^{7} a_{1} \\&a_{5}=a_{1} 2^{5-1} \\&a_{5}=2^{4} a_{1}\end{aligned}[/tex]

So, ratio of a₈ to a₅ is;

= [tex]2^{7} a_{1}: 2^{4} a_{1}[/tex]

= [tex]\frac{128}{16}: 1[/tex]

= 8 : 1

Therefore, a 8th term in this series has an 8:1 ratio to the 5th term.

To know more about the geometric sequence, here

https://brainly.com/question/1509142

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