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Finding the Fourth Proportional to 1,386.72, 2,079.75 and 645.86

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Solution

The fourth proportional to 1,386.72, 2,079.75 and 645.86 is: 968.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.72 : 2,079.75 = 645.86 : x
  2. Step 2: Convert to fraction form
    1,386.72/2,079.75 = 645.86/x
  3. Step 3: Cross multiply
    1,386.72x = 2,079.75 × 645.86
  4. Step 4: Simplify right side
    1,386.72x = 1,343,230.11
  5. Step 5: Solve for x
    x = 1,343,230.11/1,386.72
  6. Step 6: Final answer
    x = 968.64

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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.