Home / 388.80-583.25-128.71

Finding the Fourth Proportional to 388.80, 583.25 and 128.71

Calculator

Solution

The fourth proportional to 388.80, 583.25 and 128.71 is: 193.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    388.80 : 583.25 = 128.71 : x
  2. Step 2: Convert to fraction form
    388.80/583.25 = 128.71/x
  3. Step 3: Cross multiply
    388.80x = 583.25 × 128.71
  4. Step 4: Simplify right side
    388.80x = 75,070.11
  5. Step 5: Solve for x
    x = 75,070.11/388.80
  6. Step 6: Final answer
    x = 193.08

Related Problems

Find fourth proportional to 194.40, 291.63 and 64.36
Half scale
Find fourth proportional to 777.60, 1,166.50 and 257.42
Double scale
Find fourth proportional to 389.80, 584.75 and 129.71
Similar ratio
Find fourth proportional to 583.20, 874.88 and 193.07
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.