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Finding the Fourth Proportional to 1,421.40, 2,129.02 and 689.44

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Solution

The fourth proportional to 1,421.40, 2,129.02 and 689.44 is: 1,032.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,421.40 : 2,129.02 = 689.44 : x
  2. Step 2: Convert to fraction form
    1,421.40/2,129.02 = 689.44/x
  3. Step 3: Cross multiply
    1,421.40x = 2,129.02 × 689.44
  4. Step 4: Simplify right side
    1,421.40x = 1,467,824.50
  5. Step 5: Solve for x
    x = 1,467,824.50/1,421.40
  6. Step 6: Final answer
    x = 1,032.66

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1.5x scale

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.