Final answer:
To estimate Martin's friend's purchase of grapes, convert 12 3/5 to an improper fraction and multiply it by 3/8. The estimate is 9/40 pounds of grapes.
Step-by-step explanation:
To estimate how many pounds of grapes Martin's friend bought, we can use compatible fractions. Martin bought 12 3/5 pounds of grapes. His friend bought 3/8 of that amount.
Step 1: Convert 12 3/5 to an improper fraction.
12 3/5 = (5 * 12 + 3)/5 = 63/5
Step 2: Multiply the improper fraction by 3/8.
(63/5) * (3/8) = (63 * 3)/(5 * 8) = 9/40
Therefore, Martin's friend estimated about 9/40 pounds of grapes.