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Finding the Fourth Proportional to 715.81, 987.76 and 421.07

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Solution

The fourth proportional to 715.81, 987.76 and 421.07 is: 581.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.81 : 987.76 = 421.07 : x
  2. Step 2: Convert to fraction form
    715.81/987.76 = 421.07/x
  3. Step 3: Cross multiply
    715.81x = 987.76 × 421.07
  4. Step 4: Simplify right side
    715.81x = 415,916.10
  5. Step 5: Solve for x
    x = 415,916.10/715.81
  6. Step 6: Final answer
    x = 581.04

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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.