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Finding the Fourth Proportional to 1,688.64, 2,330.88 and 990

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Solution

The fourth proportional to 1,688.64, 2,330.88 and 990 is: 1,366.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,688.64 : 2,330.88 = 990 : x
  2. Step 2: Convert to fraction form
    1,688.64/2,330.88 = 990/x
  3. Step 3: Cross multiply
    1,688.64x = 2,330.88 × 990
  4. Step 4: Simplify right side
    1,688.64x = 2,307,571.20
  5. Step 5: Solve for x
    x = 2,307,571.20/1,688.64
  6. Step 6: Final answer
    x = 1,366.53

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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.