Multiple Select Question

Joslyn is planting daisy seeds in a flower garden. Each day, she plants a different number of seeds. The list below shows the number of seeds Joslyn planted on each of the first six days.
1, 2, 4, 8, 16, 32

Joslyn wants to determine the number of daisy seeds, d, she should plant on the nth day. Which statements below are true? Select two that apply.

A.
The sequence is arithmetic.

B.
The sequence is geometric.

C.
The sequence is represented by d = 2n
.

D.
The sequence is represented by d=2n-1
.

E.
The sequence is represented by d= 2^n
.

F.
The sequence is represented by d = 2^n-1
.

1 answer

To analyze the series of numbers Joslyn planted (1, 2, 4, 8, 16, 32), we can look at the characteristics of the sequence and determine which statements are true.

  1. Is the sequence arithmetic?

    • An arithmetic sequence is characterized by a constant difference between consecutive terms. Here, the differences are not constant (1, 2, 4, 8, 16, etc.), so A is false.
  2. Is the sequence geometric?

    • A geometric sequence has a constant ratio between consecutive terms. In this case, each term is doubled (the ratio is 2). Therefore, the sequence is geometric, so B is true.
  3. Is the sequence represented by \( d = 2^n \)?

    • For \( n = 1 \), \( d = 2^1 = 2 \) (2nd term); for \( n = 2 \), \( d = 2^2 = 4 \) (3rd term), and so on. This would not accurately represent the first term (1 is the first term, which corresponds to \( d = 2^0 = 1 \) if we start counting from \( n = 0 \)). Thus C is false.
  4. Is the sequence represented by \( d = 2^{n-1} \)?

    • For \( n = 1 \), \( d = 2^{1-1} = 2^0 = 1 \) (1st term), for \( n = 2 \), \( d = 2^{2-1} = 2^1 = 2 \) (2nd term), etc. This works correctly and matches the provided sequence, so D is true.
  5. Is the sequence represented by \( d = 2^n \)? (duplicate assessment, needs explicit checking).

    • As we previously assessed, this representation does not start correctly at 1 for the first term. Thus, E is false.
  6. Is the sequence represented by \( d = 2^{n-1} \)? (duplicate assessment, confirmation necessary).

    • As we have confirmed working through values previously, and it matches, so this reinforces D is true.
  7. Is the sequence represented by \( d = 2^n - 1 \)?

    • If \( n = 1 \), then \( d = 2^1 - 1 = 1 \) (1st term); however, for other values, this will lead to incorrect results. Hence F is false.

Based on this assessment, the true statements are:

B. The sequence is geometric.

D. The sequence is represented by \( d = 2^{n-1} \).