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Finding the Fourth Proportional to 78.64, 118.64 and 74.32

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Solution

The fourth proportional to 78.64, 118.64 and 74.32 is: 112.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.64 : 118.64 = 74.32 : x
  2. Step 2: Convert to fraction form
    78.64/118.64 = 74.32/x
  3. Step 3: Cross multiply
    78.64x = 118.64 × 74.32
  4. Step 4: Simplify right side
    78.64x = 8,817.32
  5. Step 5: Solve for x
    x = 8,817.32/78.64
  6. Step 6: Final answer
    x = 112.12

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.