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Finding the Fourth Proportional to 715.68, 987.86 and 421

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Solution

The fourth proportional to 715.68, 987.86 and 421 is: 581.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.68 : 987.86 = 421 : x
  2. Step 2: Convert to fraction form
    715.68/987.86 = 421/x
  3. Step 3: Cross multiply
    715.68x = 987.86 × 421
  4. Step 4: Simplify right side
    715.68x = 415,889.06
  5. Step 5: Solve for x
    x = 415,889.06/715.68
  6. Step 6: Final answer
    x = 581.11

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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.