How many three-symbol codes can be formed from the letters I,S,P, and Y without repetition?

4*3*2 = 24

I S P

I S Y

I P S

I P Y

I Y S

I Y P

S I P

S I Y

S P I

S P Y

S Y I

S Y P

P I S

P I Y

P S I

P S Y

P Y I

P Y S

Y I S

Y I P

Y S I

Y S P

Y P I

Y P S

To find the number of three-symbol codes that can be formed from the letters I, S, P, and Y without repetition, you can use the concept of combinations.

Since there are four letters to choose from, you can construct a three-symbol code by selecting three letters from the available options without repetition.

To calculate the number of combinations, you can use the formula for combinations:

C(n, r) = n! / (r!(n - r)!)

Where:
- n is the total number of items (in this case, the number of letters available)
- r is the number of items to be chosen (in this case, the number of symbols in the code)

Using this formula, let's calculate the number of three-symbol codes:

C(4, 3) = 4! / (3!(4 - 3)!)
= 4! / (3! * 1!)
= (4 * 3 * 2 * 1) / (3 * 2 * 1 * 1)
= 4

Therefore, there are four different three-symbol codes that can be formed from the letters I, S, P, and Y without repetition.