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Finding the Fourth Proportional to 1,275.78, 1,758.80 and 855.40

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Solution

The fourth proportional to 1,275.78, 1,758.80 and 855.40 is: 1,179.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,275.78 : 1,758.80 = 855.40 : x
  2. Step 2: Convert to fraction form
    1,275.78/1,758.80 = 855.40/x
  3. Step 3: Cross multiply
    1,275.78x = 1,758.80 × 855.40
  4. Step 4: Simplify right side
    1,275.78x = 1,504,477.52
  5. Step 5: Solve for x
    x = 1,504,477.52/1,275.78
  6. Step 6: Final answer
    x = 1,179.26

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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.