Home / 821.12-1,229.12-639.04

Finding the Fourth Proportional to 821.12, 1,229.12 and 639.04

Calculator

Solution

The fourth proportional to 821.12, 1,229.12 and 639.04 is: 956.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.12 : 1,229.12 = 639.04 : x
  2. Step 2: Convert to fraction form
    821.12/1,229.12 = 639.04/x
  3. Step 3: Cross multiply
    821.12x = 1,229.12 × 639.04
  4. Step 4: Simplify right side
    821.12x = 785,456.84
  5. Step 5: Solve for x
    x = 785,456.84/821.12
  6. Step 6: Final answer
    x = 956.57

Related Problems

Find fourth proportional to 410.56, 614.56 and 319.52
Half scale
Find fourth proportional to 1,642.24, 2,458.24 and 1,278.08
Double scale
Find fourth proportional to 822.12, 1,230.62 and 640.04
Similar ratio
Find fourth proportional to 1,231.68, 1,843.68 and 958.56
1.5x scale

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.