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Finding the Fourth Proportional to 875.28, 1,312.20 and 388.80

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Solution

The fourth proportional to 875.28, 1,312.20 and 388.80 is: 582.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    875.28 : 1,312.20 = 388.80 : x
  2. Step 2: Convert to fraction form
    875.28/1,312.20 = 388.80/x
  3. Step 3: Cross multiply
    875.28x = 1,312.20 × 388.80
  4. Step 4: Simplify right side
    875.28x = 510,183.36
  5. Step 5: Solve for x
    x = 510,183.36/875.28
  6. Step 6: Final answer
    x = 582.88

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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.