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Finding the Fourth Proportional to 1,187.40, 1,638.62 and 663.47

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Solution

The fourth proportional to 1,187.40, 1,638.62 and 663.47 is: 915.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.40 : 1,638.62 = 663.47 : x
  2. Step 2: Convert to fraction form
    1,187.40/1,638.62 = 663.47/x
  3. Step 3: Cross multiply
    1,187.40x = 1,638.62 × 663.47
  4. Step 4: Simplify right side
    1,187.40x = 1,087,175.21
  5. Step 5: Solve for x
    x = 1,087,175.21/1,187.40
  6. Step 6: Final answer
    x = 915.59

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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.