Home / 661.80-913.28-399.76

Finding the Fourth Proportional to 661.80, 913.28 and 399.76

Calculator

Solution

The fourth proportional to 661.80, 913.28 and 399.76 is: 551.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.80 : 913.28 = 399.76 : x
  2. Step 2: Convert to fraction form
    661.80/913.28 = 399.76/x
  3. Step 3: Cross multiply
    661.80x = 913.28 × 399.76
  4. Step 4: Simplify right side
    661.80x = 365,092.81
  5. Step 5: Solve for x
    x = 365,092.81/661.80
  6. Step 6: Final answer
    x = 551.67

Related Problems

Find fourth proportional to 330.90, 456.64 and 199.88
Half scale
Find fourth proportional to 1,323.60, 1,826.56 and 799.52
Double scale
Find fourth proportional to 662.80, 914.66 and 400.76
Similar ratio
Find fourth proportional to 992.70, 1,369.92 and 599.64
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.