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Finding the Fourth Proportional to 860.70, 1,290.78 and 312.96

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Solution

The fourth proportional to 860.70, 1,290.78 and 312.96 is: 469.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.70 : 1,290.78 = 312.96 : x
  2. Step 2: Convert to fraction form
    860.70/1,290.78 = 312.96/x
  3. Step 3: Cross multiply
    860.70x = 1,290.78 × 312.96
  4. Step 4: Simplify right side
    860.70x = 403,962.51
  5. Step 5: Solve for x
    x = 403,962.51/860.70
  6. Step 6: Final answer
    x = 469.34

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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.