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Finding the Fourth Proportional to 860.79, 1,290.87 and 312.84

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Solution

The fourth proportional to 860.79, 1,290.87 and 312.84 is: 469.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.79 : 1,290.87 = 312.84 : x
  2. Step 2: Convert to fraction form
    860.79/1,290.87 = 312.84/x
  3. Step 3: Cross multiply
    860.79x = 1,290.87 × 312.84
  4. Step 4: Simplify right side
    860.79x = 403,835.77
  5. Step 5: Solve for x
    x = 403,835.77/860.79
  6. Step 6: Final answer
    x = 469.15

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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.