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Finding the Fourth Proportional to 78.72, 108.53 and 65.63

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Solution

The fourth proportional to 78.72, 108.53 and 65.63 is: 90.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.72 : 108.53 = 65.63 : x
  2. Step 2: Convert to fraction form
    78.72/108.53 = 65.63/x
  3. Step 3: Cross multiply
    78.72x = 108.53 × 65.63
  4. Step 4: Simplify right side
    78.72x = 7,121.95
  5. Step 5: Solve for x
    x = 7,121.95/78.72
  6. Step 6: Final answer
    x = 90.47

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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.