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Finding the Fourth Proportional to 74.64, 102.78 and 64.79

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Solution

The fourth proportional to 74.64, 102.78 and 64.79 is: 89.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    74.64 : 102.78 = 64.79 : x
  2. Step 2: Convert to fraction form
    74.64/102.78 = 64.79/x
  3. Step 3: Cross multiply
    74.64x = 102.78 × 64.79
  4. Step 4: Simplify right side
    74.64x = 6,659.12
  5. Step 5: Solve for x
    x = 6,659.12/74.64
  6. Step 6: Final answer
    x = 89.22

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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.