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Finding the Fourth Proportional to 909.40, 1,261.42 and 878.32

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Solution

The fourth proportional to 909.40, 1,261.42 and 878.32 is: 1,218.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    909.40 : 1,261.42 = 878.32 : x
  2. Step 2: Convert to fraction form
    909.40/1,261.42 = 878.32/x
  3. Step 3: Cross multiply
    909.40x = 1,261.42 × 878.32
  4. Step 4: Simplify right side
    909.40x = 1,107,930.41
  5. Step 5: Solve for x
    x = 1,107,930.41/909.40
  6. Step 6: Final answer
    x = 1,218.31

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.