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Finding the Fourth Proportional to 72.36, 99.90 and 56.79

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Solution

The fourth proportional to 72.36, 99.90 and 56.79 is: 78.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.36 : 99.90 = 56.79 : x
  2. Step 2: Convert to fraction form
    72.36/99.90 = 56.79/x
  3. Step 3: Cross multiply
    72.36x = 99.90 × 56.79
  4. Step 4: Simplify right side
    72.36x = 5,673.32
  5. Step 5: Solve for x
    x = 5,673.32/72.36
  6. Step 6: Final answer
    x = 78.40

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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.