In an experiment to determine the acceleration due to gravity g, the formula used for the time period of a periodic motion is $$T = 2 \pi \sqrt{\frac{7(R - r)}{5g}}$$. The values of R and r are measured to be $$(60 \pm 1)$$ mm and $$(10 \pm 1)$$ mm, respectively. In five successive measurements, the time period is found to be 0.52 s, 0.56 s, 0.57 s, 0.54 s and 0.59 s. The least count of the watch used for the measurement of time period is 0.01 s. Which of the following statement(s) is(are) true?