The combination helps us to know the number of ways an object can be arranged without a particular manner. A combination is denoted by 'C'.

$^nC_r = \dfrac{n!}{r!(n-r)!}$

where,

n is the number of choices available,

r is the choices to be made.

As it is given that the password can only be made with letters or numbers, and we know that there are only 26 letters and there are 10 numbers, therefore, the total option available is 36.

Also, it is given that the first letter of the password can only be made with letters, therefore, there are only 26 options available for the first place in the password.

The number of 8 character passwords that can be formed using letters and digits if the password must begin with a letter,

$= ^{26}C_{1} \times ^{36}C_{1} \times ^{36}C_{1} \times ^{36}C_{1} \times ^{36}C_{1} \times ^{36}C_{1} \times ^{36}C_{1} \times ^{36}C_{1} \\\\= 26 \times 31\times 31\times 31\times 31\times 31\times 31\times 31\\\\= 26 \times 31^7$

Hence, the number of 8 character passwords that can be formed using letters and digits if the password must begin with a letter is 26×31⁷.

Learn more about Combination:

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4 0

2 years ago

Mr. Beebe asks the question in lines 6-7 ("Does . . .

shusha [124]

Correct option is D. Mr. Beebe asks the question in lines 6-7 ("Does . . .

quietly") primarily in order to note an apparent inconsistency.

Mr. Beebe sounds cynical (though he says he is not) of the fact that Lucy Honeychurch is someone who plays the piano beautifully and likes to live quietly. He believes that one these both qualities will 'mingle'. In the given context, it seems like Beebe believes that a person can not be both: good at music and like to live quietly. He thinks that it is reflects an inconsistency in Lucy's personality. Thus D is the best answer.

The lines of passage were -

Does it seem reasonable that she should play piano so wonderfully, and live so quietly? I suspect that someday she shall be wonderful in both. The water-tight compartments in her will break down,

To learn more about passages from given link

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4 0

1 year ago

Question in the photo<br> Pls help

ra1l [238]

Answer:

F = $\frac{9C+160}{5}$