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Finding the Fourth Proportional to 1,256.80, 1,885.20 and 861.09

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Solution

The fourth proportional to 1,256.80, 1,885.20 and 861.09 is: 1,291.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,256.80 : 1,885.20 = 861.09 : x
  2. Step 2: Convert to fraction form
    1,256.80/1,885.20 = 861.09/x
  3. Step 3: Cross multiply
    1,256.80x = 1,885.20 × 861.09
  4. Step 4: Simplify right side
    1,256.80x = 1,623,330.40
  5. Step 5: Solve for x
    x = 1,623,330.40/1,256.80
  6. Step 6: Final answer
    x = 1,291.64

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.