Home / 620.34-855.90-399.60

Finding the Fourth Proportional to 620.34, 855.90 and 399.60

Calculator

Solution

The fourth proportional to 620.34, 855.90 and 399.60 is: 551.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.34 : 855.90 = 399.60 : x
  2. Step 2: Convert to fraction form
    620.34/855.90 = 399.60/x
  3. Step 3: Cross multiply
    620.34x = 855.90 × 399.60
  4. Step 4: Simplify right side
    620.34x = 342,017.64
  5. Step 5: Solve for x
    x = 342,017.64/620.34
  6. Step 6: Final answer
    x = 551.34

Related Problems

Find fourth proportional to 310.17, 427.95 and 199.80
Half scale
Find fourth proportional to 1,240.68, 1,711.80 and 799.20
Double scale
Find fourth proportional to 621.34, 857.28 and 400.60
Similar ratio
Find fourth proportional to 930.51, 1,283.85 and 599.40
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.