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Finding the Fourth Proportional to 1,390.71, 2,085.95 and 513.23

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Solution

The fourth proportional to 1,390.71, 2,085.95 and 513.23 is: 769.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.71 : 2,085.95 = 513.23 : x
  2. Step 2: Convert to fraction form
    1,390.71/2,085.95 = 513.23/x
  3. Step 3: Cross multiply
    1,390.71x = 2,085.95 × 513.23
  4. Step 4: Simplify right side
    1,390.71x = 1,070,578.62
  5. Step 5: Solve for x
    x = 1,070,578.62/1,390.71
  6. Step 6: Final answer
    x = 769.81

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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.