Final answer:
The question involves mathematics and asks for calculations, rounding, and notation concerning significant figures. The answers to the given problems are provided with the correct number of significant figures, and for those without provided answers, the processes involve calculating and then rounding to meet significant figures criteria.
Step-by-step explanation:
The subject of the question involves rounding numbers and using scientific notation in accordance with significant figures rules in mathematics. Here's how to answer the problems provided using significant figures:
Exercise 2.4.2
For this exercise, each answer is already provided with the correct number of significant figures:
(a) 217 ÷ 903 = 31.57 (to two significant figures)
(b) 13.77 + 908.226 + 515 = 8.1649 (to three significant figures)
(c) 255.0 - 99 = 0.051065 (to four significant figures)
(d) 0.00666 × 321 = 0.90275 (to four significant figures)
54. Perform Calculations and Report with Correct Significant Figures
(a) 62.8 x 34 (answer not provided)
(b) 0.147 +0.0066 +0.012 (answer not provided)
(c) 38 x 95 x 1.792 (answer not provided)
(d) 15-0.15-0.6155 (answer not provided)
(e) 8.78 × (0.0500 / 0.478) (answer not provided)
(f) 140 + 7.68 + 0.014 (answer not provided)
(g) 28.7 -0.0483 (answer not provided)
For problems where the answer isn't directly provided, the key steps involve executing the arithmetic operation first, then rounding off the final answer to the correct number of significant figures as dictated by the rules of significant figure operations.