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Finding the Fourth Proportional to 31.26, 42.90 and 30.60

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Solution

The fourth proportional to 31.26, 42.90 and 30.60 is: 41.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.26 : 42.90 = 30.60 : x
  2. Step 2: Convert to fraction form
    31.26/42.90 = 30.60/x
  3. Step 3: Cross multiply
    31.26x = 42.90 × 30.60
  4. Step 4: Simplify right side
    31.26x = 1,312.74
  5. Step 5: Solve for x
    x = 1,312.74/31.26
  6. Step 6: Final answer
    x = 41.99

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.