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Finding the Fourth Proportional to 1,218.42, 1,681.39 and 687.30

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Solution

The fourth proportional to 1,218.42, 1,681.39 and 687.30 is: 948.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.42 : 1,681.39 = 687.30 : x
  2. Step 2: Convert to fraction form
    1,218.42/1,681.39 = 687.30/x
  3. Step 3: Cross multiply
    1,218.42x = 1,681.39 × 687.30
  4. Step 4: Simplify right side
    1,218.42x = 1,155,611.71
  5. Step 5: Solve for x
    x = 1,155,611.71/1,218.42
  6. Step 6: Final answer
    x = 948.45

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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.