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Finding the Fourth Proportional to 1,290.08, 1,780.56 and 766.40

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Solution

The fourth proportional to 1,290.08, 1,780.56 and 766.40 is: 1,057.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.08 : 1,780.56 = 766.40 : x
  2. Step 2: Convert to fraction form
    1,290.08/1,780.56 = 766.40/x
  3. Step 3: Cross multiply
    1,290.08x = 1,780.56 × 766.40
  4. Step 4: Simplify right side
    1,290.08x = 1,364,621.18
  5. Step 5: Solve for x
    x = 1,364,621.18/1,290.08
  6. Step 6: Final answer
    x = 1,057.78

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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.