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Finding the Fourth Proportional to 715.89, 987.99 and 421.14

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Solution

The fourth proportional to 715.89, 987.99 and 421.14 is: 581.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.89 : 987.99 = 421.14 : x
  2. Step 2: Convert to fraction form
    715.89/987.99 = 421.14/x
  3. Step 3: Cross multiply
    715.89x = 987.99 × 421.14
  4. Step 4: Simplify right side
    715.89x = 416,082.11
  5. Step 5: Solve for x
    x = 416,082.11/715.89
  6. Step 6: Final answer
    x = 581.21

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.