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Finding the Fourth Proportional to 1,290.30, 1,780.02 and 818.79

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Solution

The fourth proportional to 1,290.30, 1,780.02 and 818.79 is: 1,129.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.30 : 1,780.02 = 818.79 : x
  2. Step 2: Convert to fraction form
    1,290.30/1,780.02 = 818.79/x
  3. Step 3: Cross multiply
    1,290.30x = 1,780.02 × 818.79
  4. Step 4: Simplify right side
    1,290.30x = 1,457,462.58
  5. Step 5: Solve for x
    x = 1,457,462.58/1,290.30
  6. Step 6: Final answer
    x = 1,129.55

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.