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Finding the Fourth Proportional to 11.40, 15.70 and 9.78

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Solution

The fourth proportional to 11.40, 15.70 and 9.78 is: 13.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    11.40 : 15.70 = 9.78 : x
  2. Step 2: Convert to fraction form
    11.40/15.70 = 9.78/x
  3. Step 3: Cross multiply
    11.40x = 15.70 × 9.78
  4. Step 4: Simplify right side
    11.40x = 153.55
  5. Step 5: Solve for x
    x = 153.55/11.40
  6. Step 6: Final answer
    x = 13.47

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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.