Jada is buying 4 stamps that cost $0.49 each. how can rounding be used to estimate the total cost of the stamps?
since each stamp is about $0.50, the total cost is approximately 4 + 0.5 $4.50.
since she is buying about 10 stamps, the total cost is approximately 10 × 0.49 = $4.90.
since each stamp is about $0.50, the total cost is approximately 4 x 0.5 = $2.00.
since she is buying about 10 stamps, the total cost is approximately 10 +0.49 = $10.49.

Which option identifies how kevin should proceed in the following scenario? four years ago kevin designed an mp3 player for young children. now that technology has changed, he would like to update his design to ensure that it encompasses cutting-edge techniques. by creating a third-angle projection of his ideas by designing an isometric projection of his new ideas by referring to past designs and illustrations of his original model by conferring with engineers who have improved upon similar devices