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Finding the Fourth Proportional to 1,187.40, 1,638.58 and 663.40

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Solution

The fourth proportional to 1,187.40, 1,638.58 and 663.40 is: 915.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.40 : 1,638.58 = 663.40 : x
  2. Step 2: Convert to fraction form
    1,187.40/1,638.58 = 663.40/x
  3. Step 3: Cross multiply
    1,187.40x = 1,638.58 × 663.40
  4. Step 4: Simplify right side
    1,187.40x = 1,087,033.97
  5. Step 5: Solve for x
    x = 1,087,033.97/1,187.40
  6. Step 6: Final answer
    x = 915.47

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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.