Estimate = 50. We have 6 rings. We skip count in 10s six times. 10, 20, 30, 40, 50, 60

Each group consists of 10 small oval shapes.

There are 10 groups in total.

Actual count = $10 \text{ groups} \times 10 \text{ ovals/group} = 100$ ovals.

An estimate of 90 is reasonable for an actual count of 100.

• Estimate: $\boxed{90}$
• Actual: $\boxed{100}$

:

Each group consists of 5 fish.

There are 4 rows, and each row has 4 groups.
Total groups = $4 \text{ rows} \times 4 \text{ groups/row} = 16$ groups.

Actual count = $16 \text{ groups} \times 5 \text{ fish/group} = 80$ fish.

An estimate of 90 is reasonable for an actual count of 80.

• Estimate: $\boxed{90}$
• Actual: $\boxed{80}$