To get the most precise estimate for the sum of $4,218 + 3,891$, which rounding method is best?

Rounding both numbers to the nearest thousand

Rounding both numbers to the nearest hundred

Rounding only the first number to the nearest thousand

Rounding only the second number to the nearest hundred

A farmer calculates that she needs 530 pounds of fertilizer. It is sold in 50-pound bags. Why must she buy 11 bags (550 pounds) instead of 10 bags (500 pounds)?

Because 530 is closer to 550 than to 500

Because standard rounding rules say to round 3 down

To ensure she has enough fertilizer for her entire field