Total number of characters in the computer password =7.
Number of letters used = 4 letters.
Total numbers used = 3 numbers.
There are 26 English alphabets.
For first character number of options = 26.
For second character number of options = 26.
For third character number of options = 26.
For fourth character number of options = 26.
For fifth character number of options(number from 0 to 9) = 10.
For sixth character number of options = 10.
For seventh character number of options = 10.
Therefore, total number of different possible passwords = 26× 26× 26× 26× 10×10×10
= 456976000.
Therefore, correct option is 3rd option c. 456,976,000.
