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Finding the Fourth Proportional to 64.92, 89.70 and 56.74

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Solution

The fourth proportional to 64.92, 89.70 and 56.74 is: 78.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    64.92 : 89.70 = 56.74 : x
  2. Step 2: Convert to fraction form
    64.92/89.70 = 56.74/x
  3. Step 3: Cross multiply
    64.92x = 89.70 × 56.74
  4. Step 4: Simplify right side
    64.92x = 5,089.58
  5. Step 5: Solve for x
    x = 5,089.58/64.92
  6. Step 6: Final answer
    x = 78.40

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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.