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Finding the Fourth Proportional to 64.40, 90.40 and 64.40

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Solution

The fourth proportional to 64.40, 90.40 and 64.40 is: 90.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    64.40 : 90.40 = 64.40 : x
  2. Step 2: Convert to fraction form
    64.40/90.40 = 64.40/x
  3. Step 3: Cross multiply
    64.40x = 90.40 × 64.40
  4. Step 4: Simplify right side
    64.40x = 5,821.76
  5. Step 5: Solve for x
    x = 5,821.76/64.40
  6. Step 6: Final answer
    x = 90.40

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Why These Related Problems?

These problems maintain the same ratio (1.40) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.