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Finding the Fourth Proportional to 1,386.40, 1,913.21 and 756.91

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Solution

The fourth proportional to 1,386.40, 1,913.21 and 756.91 is: 1,044.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.40 : 1,913.21 = 756.91 : x
  2. Step 2: Convert to fraction form
    1,386.40/1,913.21 = 756.91/x
  3. Step 3: Cross multiply
    1,386.40x = 1,913.21 × 756.91
  4. Step 4: Simplify right side
    1,386.40x = 1,448,127.78
  5. Step 5: Solve for x
    x = 1,448,127.78/1,386.40
  6. Step 6: Final answer
    x = 1,044.52

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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.