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Finding the Fourth Proportional to 992.09, 1,368.51 and 642.78

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Solution

The fourth proportional to 992.09, 1,368.51 and 642.78 is: 886.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    992.09 : 1,368.51 = 642.78 : x
  2. Step 2: Convert to fraction form
    992.09/1,368.51 = 642.78/x
  3. Step 3: Cross multiply
    992.09x = 1,368.51 × 642.78
  4. Step 4: Simplify right side
    992.09x = 879,650.86
  5. Step 5: Solve for x
    x = 879,650.86/992.09
  6. Step 6: Final answer
    x = 886.67

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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.