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Finding the Fourth Proportional to 715.14, 1,071.54 and 390.78

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Solution

The fourth proportional to 715.14, 1,071.54 and 390.78 is: 585.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.14 : 1,071.54 = 390.78 : x
  2. Step 2: Convert to fraction form
    715.14/1,071.54 = 390.78/x
  3. Step 3: Cross multiply
    715.14x = 1,071.54 × 390.78
  4. Step 4: Simplify right side
    715.14x = 418,736.40
  5. Step 5: Solve for x
    x = 418,736.40/715.14
  6. Step 6: Final answer
    x = 585.53

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.