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Finding the Fourth Proportional to 1,290.68, 1,780.56 and 1,042.80

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Solution

The fourth proportional to 1,290.68, 1,780.56 and 1,042.80 is: 1,438.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.68 : 1,780.56 = 1,042.80 : x
  2. Step 2: Convert to fraction form
    1,290.68/1,780.56 = 1,042.80/x
  3. Step 3: Cross multiply
    1,290.68x = 1,780.56 × 1,042.80
  4. Step 4: Simplify right side
    1,290.68x = 1,856,767.97
  5. Step 5: Solve for x
    x = 1,856,767.97/1,290.68
  6. Step 6: Final answer
    x = 1,438.60

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1.5x scale

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.