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Finding the Fourth Proportional to 947.40, 1,421.10 and 928.20

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Solution

The fourth proportional to 947.40, 1,421.10 and 928.20 is: 1,392.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    947.40 : 1,421.10 = 928.20 : x
  2. Step 2: Convert to fraction form
    947.40/1,421.10 = 928.20/x
  3. Step 3: Cross multiply
    947.40x = 1,421.10 × 928.20
  4. Step 4: Simplify right side
    947.40x = 1,319,065.02
  5. Step 5: Solve for x
    x = 1,319,065.02/947.40
  6. Step 6: Final answer
    x = 1,392.30

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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.