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Finding the Fourth Proportional to 870.40, 1,305.69 and 285.45

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Solution

The fourth proportional to 870.40, 1,305.69 and 285.45 is: 428.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.40 : 1,305.69 = 285.45 : x
  2. Step 2: Convert to fraction form
    870.40/1,305.69 = 285.45/x
  3. Step 3: Cross multiply
    870.40x = 1,305.69 × 285.45
  4. Step 4: Simplify right side
    870.40x = 372,707.52
  5. Step 5: Solve for x
    x = 372,707.52/870.40
  6. Step 6: Final answer
    x = 428.20

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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.