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Finding the Fourth Proportional to 438.79, 655.07 and 390.19

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Solution

The fourth proportional to 438.79, 655.07 and 390.19 is: 582.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    438.79 : 655.07 = 390.19 : x
  2. Step 2: Convert to fraction form
    438.79/655.07 = 390.19/x
  3. Step 3: Cross multiply
    438.79x = 655.07 × 390.19
  4. Step 4: Simplify right side
    438.79x = 255,599.64
  5. Step 5: Solve for x
    x = 255,599.64/438.79
  6. Step 6: Final answer
    x = 582.51

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.