Home / 645.85-969.13-399.40

Finding the Fourth Proportional to 645.85, 969.13 and 399.40

Calculator

Solution

The fourth proportional to 645.85, 969.13 and 399.40 is: 599.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.85 : 969.13 = 399.40 : x
  2. Step 2: Convert to fraction form
    645.85/969.13 = 399.40/x
  3. Step 3: Cross multiply
    645.85x = 969.13 × 399.40
  4. Step 4: Simplify right side
    645.85x = 387,068.60
  5. Step 5: Solve for x
    x = 387,068.60/645.85
  6. Step 6: Final answer
    x = 599.32

Related Problems

Find fourth proportional to 322.93, 484.57 and 199.70
Half scale
Find fourth proportional to 1,291.70, 1,938.26 and 798.80
Double scale
Find fourth proportional to 646.85, 970.63 and 400.40
Similar ratio
Find fourth proportional to 968.78, 1,453.70 and 599.10
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.