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Finding the Fourth Proportional to 715.12, 987 and 491.36

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Solution

The fourth proportional to 715.12, 987 and 491.36 is: 678.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.12 : 987 = 491.36 : x
  2. Step 2: Convert to fraction form
    715.12/987 = 491.36/x
  3. Step 3: Cross multiply
    715.12x = 987 × 491.36
  4. Step 4: Simplify right side
    715.12x = 484,972.32
  5. Step 5: Solve for x
    x = 484,972.32/715.12
  6. Step 6: Final answer
    x = 678.17

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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.