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Finding the Fourth Proportional to 1,386, 1,912.68 and 765

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Solution

The fourth proportional to 1,386, 1,912.68 and 765 is: 1,055.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386 : 1,912.68 = 765 : x
  2. Step 2: Convert to fraction form
    1,386/1,912.68 = 765/x
  3. Step 3: Cross multiply
    1,386x = 1,912.68 × 765
  4. Step 4: Simplify right side
    1,386x = 1,463,200.20
  5. Step 5: Solve for x
    x = 1,463,200.20/1,386
  6. Step 6: Final answer
    x = 1,055.70

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.