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The number of students in a school who have heard a rumor at time, t, is modeled by a geometric sequence,

where the rumor was started on first day of school (day 1). If there were 32 students that have heard the rumor on day 3, and 1,024 students that have heard the rumor on day 8, then what is the number of students that have heard the rumor on day 6?

(A) 256
(B) 512
(C) 64
(D) 128

User Hfimy
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1 Answer

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Final answer:

The number of students that have heard the rumor on day 6 is 256, found by identifying the common ratio in the geometric sequence and then calculating the 6th term. Therefore correct option is A

Step-by-step explanation:

To solve the problem of calculating the number of students that have heard a rumor on day 6 given a geometric sequence, we first recognize that we have information about days 3 and 8. We can use the formula for the nth term of a geometric sequence, which is a_n = a_1 * r^(n-1), where a_1 is the first term and r is the common ratio.

First, we find the common ratio using the information given for days 3 and 8:

a_3 = 32, a_8 = 1024

Because the days are equidistant, we can divide the term of day 8 by the term of day 3 to find r^5 (since 8 - 3 = 5):

1024 / 32 = r^5

32 = r^5

r = 2

Now, to find the number of students that have heard the rumor on day 6, we calculate the 6th term of the sequence:

a_6 = a_1 * r^(6-1)

We don't have a_1, but we can use a_3 to express a_6:

a_6 = (a_3 / r^(3-1)) * r^(6-1)

a_6 = (32 / r^2) * r^5

a_6 = (32 / 2^2) * 2^5

a_6 = (32 / 4) * 32

a_6 = 8 * 32

a_6 = 256

The number of students that have heard the rumor on day 6 is 256 students, which corresponds with option (A).

User PASUMPON V N
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