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Finding the Fourth Proportional to 390.96, 540 and 317.55

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Solution

The fourth proportional to 390.96, 540 and 317.55 is: 438.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.96 : 540 = 317.55 : x
  2. Step 2: Convert to fraction form
    390.96/540 = 317.55/x
  3. Step 3: Cross multiply
    390.96x = 540 × 317.55
  4. Step 4: Simplify right side
    390.96x = 171,477
  5. Step 5: Solve for x
    x = 171,477/390.96
  6. Step 6: Final answer
    x = 438.60

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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.