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Finding the Fourth Proportional to 611.40, 842.88 and 390.24

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Solution

The fourth proportional to 611.40, 842.88 and 390.24 is: 537.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    611.40 : 842.88 = 390.24 : x
  2. Step 2: Convert to fraction form
    611.40/842.88 = 390.24/x
  3. Step 3: Cross multiply
    611.40x = 842.88 × 390.24
  4. Step 4: Simplify right side
    611.40x = 328,925.49
  5. Step 5: Solve for x
    x = 328,925.49/611.40
  6. Step 6: Final answer
    x = 537.99

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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.