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Finding the Fourth Proportional to 858.81, 1,288.29 and 390.59

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Solution

The fourth proportional to 858.81, 1,288.29 and 390.59 is: 585.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.81 : 1,288.29 = 390.59 : x
  2. Step 2: Convert to fraction form
    858.81/1,288.29 = 390.59/x
  3. Step 3: Cross multiply
    858.81x = 1,288.29 × 390.59
  4. Step 4: Simplify right side
    858.81x = 503,186.75
  5. Step 5: Solve for x
    x = 503,186.75/858.81
  6. Step 6: Final answer
    x = 585.91

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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.