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Finding the Fourth Proportional to 186.40, 279.56 and 78.28

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Solution

The fourth proportional to 186.40, 279.56 and 78.28 is: 117.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    186.40 : 279.56 = 78.28 : x
  2. Step 2: Convert to fraction form
    186.40/279.56 = 78.28/x
  3. Step 3: Cross multiply
    186.40x = 279.56 × 78.28
  4. Step 4: Simplify right side
    186.40x = 21,883.96
  5. Step 5: Solve for x
    x = 21,883.96/186.40
  6. Step 6: Final answer
    x = 117.40

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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.