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Finding the Fourth Proportional to 30.31, 45.40 and 18.90

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Solution

The fourth proportional to 30.31, 45.40 and 18.90 is: 28.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.31 : 45.40 = 18.90 : x
  2. Step 2: Convert to fraction form
    30.31/45.40 = 18.90/x
  3. Step 3: Cross multiply
    30.31x = 45.40 × 18.90
  4. Step 4: Simplify right side
    30.31x = 858.06
  5. Step 5: Solve for x
    x = 858.06/30.31
  6. Step 6: Final answer
    x = 28.31

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.