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Finding the Fourth Proportional to 1,420.68, 2,128.19 and 1,128.68

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Solution

The fourth proportional to 1,420.68, 2,128.19 and 1,128.68 is: 1,690.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,420.68 : 2,128.19 = 1,128.68 : x
  2. Step 2: Convert to fraction form
    1,420.68/2,128.19 = 1,128.68/x
  3. Step 3: Cross multiply
    1,420.68x = 2,128.19 × 1,128.68
  4. Step 4: Simplify right side
    1,420.68x = 2,402,037.35
  5. Step 5: Solve for x
    x = 2,402,037.35/1,420.68
  6. Step 6: Final answer
    x = 1,690.76

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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.