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Finding the Fourth Proportional to 51.90, 71.65 and 31.20

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Solution

The fourth proportional to 51.90, 71.65 and 31.20 is: 43.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    51.90 : 71.65 = 31.20 : x
  2. Step 2: Convert to fraction form
    51.90/71.65 = 31.20/x
  3. Step 3: Cross multiply
    51.90x = 71.65 × 31.20
  4. Step 4: Simplify right side
    51.90x = 2,235.07
  5. Step 5: Solve for x
    x = 2,235.07/51.90
  6. Step 6: Final answer
    x = 43.06

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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.