Home / 789.76-1,089.60-479.20

Finding the Fourth Proportional to 789.76, 1,089.60 and 479.20

Calculator

Solution

The fourth proportional to 789.76, 1,089.60 and 479.20 is: 661.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    789.76 : 1,089.60 = 479.20 : x
  2. Step 2: Convert to fraction form
    789.76/1,089.60 = 479.20/x
  3. Step 3: Cross multiply
    789.76x = 1,089.60 × 479.20
  4. Step 4: Simplify right side
    789.76x = 522,136.32
  5. Step 5: Solve for x
    x = 522,136.32/789.76
  6. Step 6: Final answer
    x = 661.13

Related Problems

Find fourth proportional to 394.88, 544.80 and 239.60
Half scale
Find fourth proportional to 1,579.52, 2,179.20 and 958.40
Double scale
Find fourth proportional to 790.76, 1,090.98 and 480.20
Similar ratio
Find fourth proportional to 1,184.64, 1,634.40 and 718.80
1.5x scale

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.