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Finding the Fourth Proportional to 860.99, 1,291.50 and 399.15

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Solution

The fourth proportional to 860.99, 1,291.50 and 399.15 is: 598.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.99 : 1,291.50 = 399.15 : x
  2. Step 2: Convert to fraction form
    860.99/1,291.50 = 399.15/x
  3. Step 3: Cross multiply
    860.99x = 1,291.50 × 399.15
  4. Step 4: Simplify right side
    860.99x = 515,502.23
  5. Step 5: Solve for x
    x = 515,502.23/860.99
  6. Step 6: Final answer
    x = 598.74

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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.