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Finding the Fourth Proportional to 1,420.36, 2,128.21 and 871.38

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Solution

The fourth proportional to 1,420.36, 2,128.21 and 871.38 is: 1,305.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,420.36 : 2,128.21 = 871.38 : x
  2. Step 2: Convert to fraction form
    1,420.36/2,128.21 = 871.38/x
  3. Step 3: Cross multiply
    1,420.36x = 2,128.21 × 871.38
  4. Step 4: Simplify right side
    1,420.36x = 1,854,477.45
  5. Step 5: Solve for x
    x = 1,854,477.45/1,420.36
  6. Step 6: Final answer
    x = 1,305.64

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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.