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Finding the Fourth Proportional to 1,266.40, 1,900.80 and 780.40

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Solution

The fourth proportional to 1,266.40, 1,900.80 and 780.40 is: 1,171.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,266.40 : 1,900.80 = 780.40 : x
  2. Step 2: Convert to fraction form
    1,266.40/1,900.80 = 780.40/x
  3. Step 3: Cross multiply
    1,266.40x = 1,900.80 × 780.40
  4. Step 4: Simplify right side
    1,266.40x = 1,483,384.32
  5. Step 5: Solve for x
    x = 1,483,384.32/1,266.40
  6. Step 6: Final answer
    x = 1,171.34

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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.