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Finding the Fourth Proportional to 1,420.05, 2,128.86 and 688.62

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Solution

The fourth proportional to 1,420.05, 2,128.86 and 688.62 is: 1,032.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,420.05 : 2,128.86 = 688.62 : x
  2. Step 2: Convert to fraction form
    1,420.05/2,128.86 = 688.62/x
  3. Step 3: Cross multiply
    1,420.05x = 2,128.86 × 688.62
  4. Step 4: Simplify right side
    1,420.05x = 1,465,975.57
  5. Step 5: Solve for x
    x = 1,465,975.57/1,420.05
  6. Step 6: Final answer
    x = 1,032.34

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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.