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Finding the Fourth Proportional to 1,218.67, 1,681.64 and 687.51

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Solution

The fourth proportional to 1,218.67, 1,681.64 and 687.51 is: 948.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.67 : 1,681.64 = 687.51 : x
  2. Step 2: Convert to fraction form
    1,218.67/1,681.64 = 687.51/x
  3. Step 3: Cross multiply
    1,218.67x = 1,681.64 × 687.51
  4. Step 4: Simplify right side
    1,218.67x = 1,156,140.23
  5. Step 5: Solve for x
    x = 1,156,140.23/1,218.67
  6. Step 6: Final answer
    x = 948.69

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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.