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Finding the Fourth Proportional to 777.12, 1,170.93 and 643.16

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Solution

The fourth proportional to 777.12, 1,170.93 and 643.16 is: 969.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    777.12 : 1,170.93 = 643.16 : x
  2. Step 2: Convert to fraction form
    777.12/1,170.93 = 643.16/x
  3. Step 3: Cross multiply
    777.12x = 1,170.93 × 643.16
  4. Step 4: Simplify right side
    777.12x = 753,095.34
  5. Step 5: Solve for x
    x = 753,095.34/777.12
  6. Step 6: Final answer
    x = 969.09

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.