To find the cost of 7 muffins, we first need to determine the cost of one muffin.
Jacob buys 4 muffins for $5.00, so the cost per muffin is:
\[ \text{Cost per muffin} = \frac{5.00}{4} = 1.25 \]
Now, we can find the cost for 7 muffins:
\[ \text{Cost for 7 muffins} = 7 \times 1.25 = 8.75 \]
So, the cost of 7 muffins is $8.75.