Ask question

Ask question

All categories

3 years ago

13

Suppose that 30% of students prefer to write with a mechanical pencil. suppose we sample students, one at a time, and stop as so

on as we have selected one who prefers to write with a mechanical pencil. the probability that we will select 2 or fewer students is

1 answer:

tia_tia [17]3 years ago

6 0

Probability that first student prefers mechanical pen = 0.30
P(first student does not and second student does) = 0.70 * 0.3 = 0.21)

P( selecting 2 or fweer) = 0.30+ 0.21) = 0.51 or 51%

You might be interested in

X=1/16y^2 the directrix of the parabola is

yan [13]

To solve this problem you must apply the proccedure shown below:

1. You have the following equation of a parabola, given in the problem above:

x<span>=1/16y^2

2. Then, based on the graph attached, you have:

p=y^2/4x
p=8^2/(4)(4)
p=64/16
p=4

3. The directrix is:

directrix=h-p
directrix=0-4
directrix=-4

The answer is:-4</span>

3 0

3 years ago

A recipe for 8 people includes 4 pounds of sugar. How many pounds of sugar would be necessary for 6 people?

sammy [17]

Answer:

3pound sugar .,......................

3 0

2 years ago

Wilhelmina wrote a check for $72 to pay her monthly Internet bill, but when

lesantik [10]

Answer:

her bank statement will show that she has $144 less than her checkbook balance

Step-by-step explanation:

let the amount of money in the bank before writing the check be x

after writing the check for $72, because she accidentally recorded this as a credit, here checkbook will reflect a balance of :$(x + 72)

However, the bank correctly records the debit of the $72, resulting a balance of: $(x-72)

Hence compared to her checkbook, the bank records will show an amount difference of :

(x-72) - (x + 72)

= x - 72 -x -72

= -144

i.e her bank statement will show that she has $144 less than her checkbook balance

3 0

3 years ago

Read 2 more answers

The height of a stuntperson jumping off a building that is 20 m high is modeled by the equation h = 20 -57, where t is the time

cupoosta [38]

A stuntman jumping off a 20-m-high building is modeled by the equation h = 20 – 5t2, where t is the time in seconds. A high-speed camera is ready to film him between 15 m and 10 m above the ground. For which interval of time should the camera film him?

Answer:

$1\leq t\geq \sqrt{2}$

Step-by-step explanation:

Given:

A stuntman jumping off a 20-m-high building is modeled by the equation

$h =20-5t^{2}$ -----------(1)

A high-speed camera is ready to making film between 15 m and 10 m above the ground

when the stuntman is 15m above the ground.

height $h = 15m$

Put height value in equation 1

$15 =20-5t^{2}$

$5t^{2} =20-15$

$5t^{2} =5$

$t^{2} =1$

$t =\pm1$

We know that the time is always positive, therefore $t=1$

when the stuntman is 10m above the ground.

height $h = 10m$

Put height value in equation 1

$10 =20-5t^{2}$

$5t^{2} =20-10$

$5t^{2} =10$

$t^{2} =\frac{10}{5}$

$t^{2} =2$

$t=\pm\sqrt{2}$

$t=\sqrt{2}$

Therefore ,time interval of camera film him is $1\leq t\geq \sqrt{2}$

7 0

3 years ago

2. Given a quadrilateral with vertices (−1, 3), (1, 5), (5, 1), and (3,−1):

zlopas [31]

<h2>Explanation:</h2>

In every rectangle, the two diagonals have the same length. If a quadrilateral's diagonals have the same length, that doesn't mean it has to be a rectangle, but if a parallelogram's diagonals have the same length, then it's definitely a rectangle.

So first of all, let's prove this is a parallelogram. The basic definition of a parallelogram is that it is a quadrilateral where both pairs of opposite sides are parallel.

So let's name the vertices as:

$A(-1,3) \\ \\ B(1,5) \\ \\ C(5,1) \\ \\ D(3,-1)$

First pair of opposite sides:

<u>Slope:</u>

$\text{For AB}: \\ \\ m=\frac{5-3}{1-(-1)}=1 \\ \\ \\ \text{For CD}: \\ \\ m=\frac{1-(-1)}{5-3}=1 \\ \\ \\ \text{So AB and CD are parallel}$

Second pair of opposite sides:

<u>Slope:</u>

$\text{For BC}: \\ \\ m=\frac{1-5}{5-1}=-1 \\ \\ \\ \text{For AD}: \\ \\ m=\frac{-1-3}{3-(-1)}=-1 \\ \\ \\ \text{So BC and AD are parallel}$

So in fact this is a parallelogram. The other thing we need to prove is that the diagonals measure the same. Using distance formula:

$d=\sqrt{(y_{2}-y_{1})^2+(x_{2}-x_{1})^2} \\ \\ \\ Diagonal \ BD: \\ \\ d=\sqrt{(5-(-1))^2+(1-3)^2}=2\sqrt{10} \\ \\ \\ Diagonal \ AC: \\ \\ d=\sqrt{(3-1)^2+(-5-1)^2}=2\sqrt{10} \\ \\ \\$

So the diagonals measure the same, therefore this is a rectangle.

5 0

3 years ago