Answer:
a. 3800
Explanation:
You want the product (0.82 +0.042)(4.4×10³) expressed to an appropriate number of significant figures.
Significant figures
The number of significant figures in a product is the least of the numbers of significant figures in the contributors. Here, 4.4×10³ has 2 significant figures, so the result needs to be rounded to 2 significant figures.
(0.82 +0.042)(4.4×10³) ≈ 3800
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Additional comment
This is the only answer choice with 2 significant figures, so it can be chosen on that basis alone.