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3 years ago

Randy has 4 pennies, 3 nickels, and 3 dimes in his pocket. If he randomly chooses 2

Mathematics

1 answer:

zmey [24]3 years ago

7 0

Answer: 3/10

Step-by-step explanation: by adding the number of coins up you get 10 coins, then minus how many pennies and nickels there are then it comes out with a proper fraction, no simlifying needed :)

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If a fair coin is flipped 15 times, what is the probability that there are more heads than tails?

ludmilkaskok [199]

Answer:

The probability that there are more heads than tails is equal to $\dfrac{1}{2}$ .

Step-by-step explanation:

Since the number of flips is an odd number, there can't be an equal number of heads and tails. In other words, there are either

more tails than heads, or,
more heads than tails.

Let the event that there are more heads than tails be $A$ . $\lnot A$ (i.e., not A) denotes that there are more tails than heads. Either one of these two cases must happen. As a result, $P(A) + P(\lnot A) = 1$ .

Additionally, since this coin is fair, the probability of getting a head is equal to the probability of getting a tail on each toss. That implies that (for example)

the probability of getting 7 heads out of 15 tosses will be the same as
the probability of getting 7 tails out of 15 tosses.

Due to this symmetry,

the probability of getting more heads than tails (A is true) is equal to
the probability of getting more tails than heads (A is not true.)

In other words $P(A) = P(\lnot A)$ .

Combining the two equations:

$\left\{\begin{aligned}&P(A) + P(\lnot A) = 1 \cr &P(A) = P(\lnot A)\end{aligned}\right.$ ,

$P(A) = P(\lnot A) = \dfrac{1}{2}$ .

In other words, the probability that there are more heads than tails is equal to $\dfrac{1}{2}$ .

This conclusion can be verified using the cumulative probability function for binomial distributions with $\dfrac{1}{2}$ as the probability of success.

$\begin{aligned}P(A) =& P(n \ge 8) \cr =& \sum \limits_{i = 8}^{15} {15 \choose i} (0.5)^{i} (0.5)^{15 - i}\cr =& \sum \limits_{i = 8}^{15} {15 \choose i} (0.5)^{15}\cr =& (0.5)^{15} \left({15 \choose 8} + {15 \choose 9} + \cdots + {15 \choose 15}\right) \cr =& (0.5)^{15} \left({15 \choose (15 - 8)} + {15 \choose (15 - 9)} + \cdots + {15 \choose (15 - 15)} \right) \cr =& (0.5)^{15} \left({15 \choose 7} + {15 \choose 6} + \cdots + {15 \choose 0}\right)\end{aligned}$

$\begin{aligned}\phantom{P(A)} =& \sum \limits_{i = 0}^{7} {15 \choose i} (0.5)^{15}\cr =& P(n \le 7) \cr =& P(\lnot A)\end{aligned}$ .

6 0

3 years ago

Jillian is selling boxes of cookies to raise money for her basketball team. The 10 oz. box costs $3.50, while the 16 oz. box cos

RideAnS [48]

Answer:

Jillian sold 15 ten-oz bags and 9 sixteen-oz bags.

Step-by-step explanation:

Let x represent number of 10-oz bags and y represent number of 16-oz bags.

We have been given that Jillian sold 24 boxes of cookies in total. We can represent this information in an equation as:

$x+y=24...(1)$

We are also told that 10 oz. box costs $3.50, while the 16 oz. box costs $5.00, so the cost of x 10-oz bags would be $3.50x$ and cost of y 16-oz bags would be $5y$ .

At the end of one week, she collected $97.50. We can represent this information in an equation as:

$3.5x+5y=97.50...(2)$

Now, we will use substitution method to solve our system of equations. From equation (1), we will get:

$y=24-x$

Substitute this value in equation (2):

$3.5x+5(24-x)=97.50$

$3.5x+120-5x=97.50$

$-1.5x+120=97.50$

$-1.5x+120-120=97.50-120$

$-1.5x=-22.5$

$\frac{-1.5x}{-1.5}=\frac{-22.5}{-1.5}$

$x=15$

Therefore, the number of 10-oz boxes sold be Jillian is 15.

Now, we will substitute $x=15$ in equation (1) to solve for y.

$15+y=24$

$15-15+y=24-15$

$y=9$

Therefore, the number of 16-oz boxes sold be Jillian is 9.

8 0

3 years ago

Suppose that ABCD is a trapezoid, with AB parallel to CD, and diagonals AC and BD intersecting at P. Explain why (a) triangles A

lora16 [44]

Answer:

A trapezoid ABCD is show below,

AB || CD

AC and BD are diagonals intersecting at P.

(a)

In Δ ABC and ABD,

Area of triangle ABC = Area of triangle ABD

Because,

Area of triangle ABC = 1/2 × Base × Height

Base = AB

Height = h, which is same for both the triangle that's why,

Area of triangle ABC = Area of triangle ABD

(b)

As we know that,

Area of triangle ABC = Area of triangle ABD

On subtracting the area of triangle ABP from both the triangles, we get

Area of triangle ABC - area of triangle ABP = Area of triangle ABD - area of triangle ABP

⇒ area of triangle BCP = area of triangle DAP

Hence, triangles BCP and DAP have the same area.

(c)

In triangle ABP and CDP,

∠ABP = ∠CDP (opposite interior angles are equal between two parallel lines)

∠APB = ∠CPD (opposite angles are equal)

∠BAP = ∠DCP (opposite interior angles are equal between two parallel lines)

Therefore,

By AAA similarity

Triangles ABP and CDP are similar.

(d)

In triangle BCP and DAP,

Only ∠BCP = ∠APD (opposite angles are equal).

Therefore,

Triangles BCP and DAP need not be similar.

8 0

3 years ago

I need help‼️‼️‼️‼️‼️

emmainna [20.7K]

Answer:

C angle 2

Step-by-step explanation:

Supplementary angles add to 180 degrees (or form a straight line)

The angles that form a straight line line angle 4 are either 2 or 3

3 0

3 years ago

Read 2 more answers

Work out <br> 5/25+2/50+7/100

bixtya [17]

Answer:

The answer is 31/100

Step-by-step explanation:

5/25 + 2/50 + 7/100 = 31/100

8 0

2 years ago