Answer:
[tex]C(x)=\begin{cases} 1.25x ~~\text{if}~~0<x\le5\\1.10x~~\text{if}~~5<x\le15\\1.00x~~\text{if}~~15<x\le25\\0.75x~~\text{if}~~x>25 \end{cases}[/tex]
Step-by-step explanation:
Let x represent the number of pounds of sunflower seed
Let Cₙ (x) represent the cost of buying x pound in the given interval n
Such that
[tex]C(x)=\begin{cases} C_1(x) \\.\\.\\.\\C_n(x) \end{cases}[/tex]
Let find different pieces and their conditions.
For 1 to 5 pound, the rate is 1.25/pound
Which means total cost is 1.25x when x lies is from 1 to 5. Hence
C₁(x) = 1.25x if 0 < x ≤ 5
For greater than 5 to 15 pound, the rate is 1.10/pound
Which means total cost is 1.10x when x lies is from greater than 5 to 15. Hence
C₂(x) = 1.10x if 5 < x ≤ 15
For greater than 15 to 25 pound, the rate is 1.00/pound
Which means total cost is 1.00x when x lies is from greater than 15 to 25. Hence
C₃(x) = 1.00x if 15 < x ≤ 25
For greater 25 pound, the rate is 0.75/pound
Which means total cost is 0.75x when x lies is from greater than 25. Hence
C₄(x) = 0.75x if x>25
Combine all to write the piecewise function
[tex]C(x)=\begin{cases} 1.25x ~~\text{if}~~0<x\le5\\1.10x~~\text{if}~~5<x\le15\\1.00x~~\text{if}~~15<x\le25\\0.75x~~\text{if}~~x>25 \end{cases}[/tex]