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Korvikt [17]
3 years ago
5

Assume X and Y are indepndent. Assume that X has mean 10 and standard deviation 8. Assume Y has mean 12 and standard deviation 6

. What is the standard deviation of the variable Z = X + Y. a. 8 b. 6 c. 10 d. 12
Computers and Technology
1 answer:
Vitek1552 [10]3 years ago
6 0

Answer:

\sigma_z = 10

Explanation:

Given

\bar x = 10

\sigma_x = 8

\bar y = 12

\sigma_y = 6

z = x + y

Required

\sigma_z

This is calculated as:

\sigma_z = \sqrt{Var(x) + Var(y)}

Calculate Var(x)

We have:

Var(x) = \sigma_x^2

Var(x) = 8^2

Var(x) = 64

Calculate Var(y)

We have:

Var(y) = \sigma_y^2

Var(y) = 6^2

Var(y) = 36

So, we have:

\sigma_z = \sqrt{Var(x) + Var(y)}

\sigma_z = \sqrt{64 + 36}

\sigma_z = \sqrt{100}

\sigma_z = 10

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Assume that name is a variable of type String that has been assigned a value. Write an expression whose value is a String contai
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Corrected (Modified) Question:

i. Assume that name is a variable of type String that has been assigned a value. Write an expression whose value is a String containing the last character of the value of name. So if the value of name were "Smith" the expression's value would be "h".

ii. Given a String variable named sentence that has been initialized, write an expression whose value is the number of characters in the String referred to by sentence.

Explanation of the corrected question

The whole question has been numbered (i) and (ii) just to separate or divide it into clearer sub questions.

Some parts of the question has also been removed since they are repetition of a part of the question.

Answer:

(i) name.charAt(name.length() - 1)

(ii) sentence.length()

Explanation:

No language  has been specified in the question for the code to be written in. However, I have chosen to write it in Java.

(i) In Java, to get a particular character in a string <em>str</em>, the function, charAt(x) is used, where x in the function represents the index of the character to be fetched. This is written as str.charAt(x).

In our case, x is the index of the last character in our string. To get the index of the last character in a string say <em>str</em>, the length of the string itself is used. However, indexing starts at zero. Therefore, to get the index, it will be the 1 subtracted from the length of the string as follows:

str.length() - 1

But note that, to get the length of a string, the method length() is used. For example if,

String str = "omobowale";

str.length() will return 9

Now to the question at hand, our string variable name is <em>name. </em>

Therefore to get its last character, we write:

<em>name.charAt(name.length() - 1)</em>

So if;

name = "Smith";

name.charAt(name.length() - 1) will return "h"

(ii) As explained in (i) above, to get the length (number of characters) of the variable string <em>sentence, </em>we simply write;

<em>sentence.length()</em>

<em>PS: The length of  a string is the number of characters present in the string.</em>

Hope this helps!

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