Samir recorded the number of different types of pets his friends have in the table shown below:

1 answer:

8 0

A line with 4 tick marks labeled cat,dog,rabbit, and guinea pig. Cat has 2 crosses, dog has 4 crosses, rabbit has 1 cross, and guinea pig has 4 crosses.

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Reggie was looking at a map of the school the scale shows that 1 inch equals 150 ft if the distance between his classroom in the

topjm [15]

Answer:

the actual distance is 1800 ft.

Step-by-step explanation:

Proportion states that the two fractions or ratios are equal.

Let x be the actual distance.

As per the statement:

Reggie was looking at a map of the school the scale shows that 1 inch equals 150 ft.

⇒1 inch = 150 ft.

if the distance between his classroom in the cafeteria measures 12 in on the map.

by definition of proportions we have;

$\frac{1}{150} = \frac{12}{x}$

By cross multiply we have;

$x = 12 \cdot 150 = 1,800$ ft

Therefore, the actual distance is 1800 ft.

4 0

3 years ago

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What is the formula for the expected number of successes in a binomial experiment with n trials and probability of success p? C

charle [14.2K]

Answer:

$(D)E[ X ] =np.$

Step-by-step explanation:

Given a binomial experiment with n trials and probability of success p,

$f(x)=\left(\begin{array}{c}n\\k\end{array}\right)p^x(1-p)^{n-x}, 0\leq x\leq n$

$E(X)=\sum_{x=0}^{n}xf(x)= \sum_{x=0}^{n}x\left(\begin{array}{c}n\\k\end{array}\right)p^x(1-p)^{n-x}$

Since each term of the summation is multiplied by x, the value of the term corresponding to x = 0 will be 0. Therefore the expected value becomes:

$E(X)=\sum_{x=1}^{n}x\left(\begin{array}{c}n\\x\end{array}\right)p^x(1-p)^{n-x}$

Now,

$x\left(\begin{array}{c}n\\x\end{array}\right)= \frac{xn!}{x!(n-x)!}=\frac{n!}{(x-)!(n-x)!}=\frac{n(n-1)!}{(x-1)!((n-1)-(x-1))!}=n\left(\begin{array}{c}n-1\\x-1\end{array}\right)$