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Finding the Fourth Proportional to 40.80, 56.16 and 38.64

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Solution

The fourth proportional to 40.80, 56.16 and 38.64 is: 53.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    40.80 : 56.16 = 38.64 : x
  2. Step 2: Convert to fraction form
    40.80/56.16 = 38.64/x
  3. Step 3: Cross multiply
    40.80x = 56.16 × 38.64
  4. Step 4: Simplify right side
    40.80x = 2,170.02
  5. Step 5: Solve for x
    x = 2,170.02/40.80
  6. Step 6: Final answer
    x = 53.19

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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.