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Finding the Fourth Proportional to 719.37, 1,071.90 and 642.78

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Solution

The fourth proportional to 719.37, 1,071.90 and 642.78 is: 957.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    719.37 : 1,071.90 = 642.78 : x
  2. Step 2: Convert to fraction form
    719.37/1,071.90 = 642.78/x
  3. Step 3: Cross multiply
    719.37x = 1,071.90 × 642.78
  4. Step 4: Simplify right side
    719.37x = 688,995.88
  5. Step 5: Solve for x
    x = 688,995.88/719.37
  6. Step 6: Final answer
    x = 957.78

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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.