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Finding the Fourth Proportional to 985.40, 1,477.69 and 780.47

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Solution

The fourth proportional to 985.40, 1,477.69 and 780.47 is: 1,170.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.40 : 1,477.69 = 780.47 : x
  2. Step 2: Convert to fraction form
    985.40/1,477.69 = 780.47/x
  3. Step 3: Cross multiply
    985.40x = 1,477.69 × 780.47
  4. Step 4: Simplify right side
    985.40x = 1,153,292.71
  5. Step 5: Solve for x
    x = 1,153,292.71/985.40
  6. Step 6: Final answer
    x = 1,170.38

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.