Answer: the first pair, (1.38,4.07) returns a value of 2.95 for pi.
Explanation: pi the defined as the ratio of the circumfernece of a circle to it's diameter. For the circle (diameter, circumference) (both in cm), the ratio is (4.07/1.38). That equals 2.95 for pi.
The rest of the calculations are attached. A few are closer to the accepted value of 3.14 . . . .
