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Finding the Fourth Proportional to 875.40, 1,312.18 and 388.79

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Solution

The fourth proportional to 875.40, 1,312.18 and 388.79 is: 582.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    875.40 : 1,312.18 = 388.79 : x
  2. Step 2: Convert to fraction form
    875.40/1,312.18 = 388.79/x
  3. Step 3: Cross multiply
    875.40x = 1,312.18 × 388.79
  4. Step 4: Simplify right side
    875.40x = 510,162.46
  5. Step 5: Solve for x
    x = 510,162.46/875.40
  6. Step 6: Final answer
    x = 582.78

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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.