Chapter 27 - Optical Instruments - Problems and Conceptual Exercises - Page 969: 15

(a) $3.33$ (b) $30.6$

(a) We know that $f-number=\frac{f}{D}$ We plug in the known values to obtain: $f-number=\frac{16.9m}{5.08m}$ $f-number=3.33$ (b) We know that $f-number=\frac{f}{D}$ We plug in the known values to obtain: $f-number=\frac{155.4m}{5.08m}$ $f-number=30.6$