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Finding the Fourth Proportional to 78.60, 108.61 and 71.64

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Solution

The fourth proportional to 78.60, 108.61 and 71.64 is: 99.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.60 : 108.61 = 71.64 : x
  2. Step 2: Convert to fraction form
    78.60/108.61 = 71.64/x
  3. Step 3: Cross multiply
    78.60x = 108.61 × 71.64
  4. Step 4: Simplify right side
    78.60x = 7,780.95
  5. Step 5: Solve for x
    x = 7,780.95/78.60
  6. Step 6: Final answer
    x = 99.00

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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.