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Finding the Fourth Proportional to 1,386.69, 2,079.87 and 645.84

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Solution

The fourth proportional to 1,386.69, 2,079.87 and 645.84 is: 968.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.69 : 2,079.87 = 645.84 : x
  2. Step 2: Convert to fraction form
    1,386.69/2,079.87 = 645.84/x
  3. Step 3: Cross multiply
    1,386.69x = 2,079.87 × 645.84
  4. Step 4: Simplify right side
    1,386.69x = 1,343,263.24
  5. Step 5: Solve for x
    x = 1,343,263.24/1,386.69
  6. Step 6: Final answer
    x = 968.68

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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.