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Finding the Fourth Proportional to 715.12, 987.10 and 420.28

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Solution

The fourth proportional to 715.12, 987.10 and 420.28 is: 580.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.12 : 987.10 = 420.28 : x
  2. Step 2: Convert to fraction form
    715.12/987.10 = 420.28/x
  3. Step 3: Cross multiply
    715.12x = 987.10 × 420.28
  4. Step 4: Simplify right side
    715.12x = 414,858.39
  5. Step 5: Solve for x
    x = 414,858.39/715.12
  6. Step 6: Final answer
    x = 580.12

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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.