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Finding the Fourth Proportional to 1,218.40, 1,681.68 and 776.80

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Solution

The fourth proportional to 1,218.40, 1,681.68 and 776.80 is: 1,072.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.40 : 1,681.68 = 776.80 : x
  2. Step 2: Convert to fraction form
    1,218.40/1,681.68 = 776.80/x
  3. Step 3: Cross multiply
    1,218.40x = 1,681.68 × 776.80
  4. Step 4: Simplify right side
    1,218.40x = 1,306,329.02
  5. Step 5: Solve for x
    x = 1,306,329.02/1,218.40
  6. Step 6: Final answer
    x = 1,072.17

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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.