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Finding the Fourth Proportional to 719.38, 1,071.91 and 642.78

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Solution

The fourth proportional to 719.38, 1,071.91 and 642.78 is: 957.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    719.38 : 1,071.91 = 642.78 : x
  2. Step 2: Convert to fraction form
    719.38/1,071.91 = 642.78/x
  3. Step 3: Cross multiply
    719.38x = 1,071.91 × 642.78
  4. Step 4: Simplify right side
    719.38x = 689,002.31
  5. Step 5: Solve for x
    x = 689,002.31/719.38
  6. Step 6: Final answer
    x = 957.77

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.