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Finding the Fourth Proportional to 939.02, 1,407.55 and 390.45

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Solution

The fourth proportional to 939.02, 1,407.55 and 390.45 is: 585.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    939.02 : 1,407.55 = 390.45 : x
  2. Step 2: Convert to fraction form
    939.02/1,407.55 = 390.45/x
  3. Step 3: Cross multiply
    939.02x = 1,407.55 × 390.45
  4. Step 4: Simplify right side
    939.02x = 549,577.90
  5. Step 5: Solve for x
    x = 549,577.90/939.02
  6. Step 6: Final answer
    x = 585.27

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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.