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Finding the Fourth Proportional to 715.12, 1,074.30 and 390.40

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Solution

The fourth proportional to 715.12, 1,074.30 and 390.40 is: 586.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.12 : 1,074.30 = 390.40 : x
  2. Step 2: Convert to fraction form
    715.12/1,074.30 = 390.40/x
  3. Step 3: Cross multiply
    715.12x = 1,074.30 × 390.40
  4. Step 4: Simplify right side
    715.12x = 419,406.72
  5. Step 5: Solve for x
    x = 419,406.72/715.12
  6. Step 6: Final answer
    x = 586.48

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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.