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Finding the Fourth Proportional to 56.70, 78.24 and 42.15

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Solution

The fourth proportional to 56.70, 78.24 and 42.15 is: 58.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    56.70 : 78.24 = 42.15 : x
  2. Step 2: Convert to fraction form
    56.70/78.24 = 42.15/x
  3. Step 3: Cross multiply
    56.70x = 78.24 × 42.15
  4. Step 4: Simplify right side
    56.70x = 3,297.82
  5. Step 5: Solve for x
    x = 3,297.82/56.70
  6. Step 6: Final answer
    x = 58.16

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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.