Question is down below:

The table shows the year groups of some students who use the canteen. Mr Ford wants to survey 50 of these students stratified by

igor_vitrenko [27]

7 more year 9 students than year 8 students should be surveyed, If Mr.Ford wants to survey 50 of these students stratified by year group.

Step-by-step explanation:

The given is,

Year Students

7 80

8 110

9 160

Total 350

Mr.Ford wants to survey 50 of these students stratified by year group.

Step:1

Formula to find the ratio of number of grouped students to total students,

$Ratio, r = \frac{Number of students grouped }{Total number of students}$

= $\frac{50}{350}$

= 0.1428

Step:2

Formula for Number of students surveyed from year wise,

For year 7 students,

= (Ratio) × (Students from year 7)

= 0.1428 × 80

= 11.424

≅ 11 (∵ For students we convert into whole number)

For year 8 students,

= (Ratio) × (Students from year 8 )

= 0.1428 × 110

= 15.708

≅ 16 (∵ For students we convert into whole number)

For year 8 students,

= (Ratio) × (Students from year 9 )

= 0.1428 × 160

= 22.8

≅ 23 (∵ For students we convert into whole number)

Step:3

To find How many more year 9 students than year 8 students should be in the survey

= ( Students from year 8 for group) -

( Students from year 8 for group)

= 23 - 16

= 7 students

Result:

7 more year 9 students than year 8 students should be surveyed, If Mr.Ford wants to survey 50 of these students stratified by year group.

6 0

3 years ago

Read 2 more answers

Suppose that a die-hardly-ever battery has an exponential time-to-failure distribution with a mean of 48 months. at 60 months, t

mel-nik [20]

Since the time to failure distribution is exponential, the distribution is F (n) = 1 – e ^ (-x/48)

The probability of failure between months 60 and 72 is the same as the probability that the battery will fail in 12 months, since the exponential distribution is memoryless F (12) = 0.221

7 0

4 years ago

Help me plz this is due in 5 minutes and I’m have this disorder and it makes me hard to concentrate and think imma go to the the

Alex Ar [27]

Answer:

p= 24

4p= 4(6) = 24

In a simplier way, 4 times 6

Step-by-step explanation:

5 0

3 years ago

Read 2 more answers

The population of wolves in a sanctuary has been growing by about 20 wolves a year. In 2012, there were 415 wolves in the sanctu

Masteriza [31]

Answer:

A: P = 20n +415

B: P = 20t + 375

C: Both equations agree, and in 2018 there will be about 535 wolves

D: The advantage of defining the input variable is that it helps simplify the calculation and makes it more intuitive.

Step-by-step explanation:

P = <u>Number of wolves</u>

n = <u>number of years since 2012</u>

<em>we know </em><em>in 2012</em><em> there were </em><u><em>415 wolves in the sanctuary</em></u><em>, and that the </em><em>sanctuary </em><em>has been </em><em>growing about </em><u><em>20</em></u><u><em> wolves </em></u><u><em>a year.</em></u>

we know this is correct because we are trying to create an equation that represents the number of wolves(p) throughout the years(n), so we are trying to figure out what P equals. We know that the sanctuary grows about <u>20</u> wolves a year, and n is the number of years since 2012. As well as obviously,<u> we add 415 to our equation because there is </u><u>already 415 wolves in the sanctuary.</u>

P = <u>Number of wolves</u>

t = <u>number of years since 2010</u>

x = <u>unknown variable(number of wolves in 2010)</u>

Here we are trying to identify what x is,<u> in 2012 there was 415, each year the number of wolves grew by 20.</u>

P = 40 - 415 = 375

<u>We now know there were 375 wolves in 2010</u>

<h3>Hence our equation is P = 20t + 375</h3>

<h3>C:</h3><h3>First let's plug in our first equation</h3>

P = 20n + 415

(To find n all we do is subtract 2018 and 2012, which equals 6.)

P = 20(6) + 415

(Solve)

P = 120 + 415

<em>Our first equation tells us that in 2018 there will be 535 wolves.</em>

<h3>Plug in our second equation</h3>

P = 20t + 375

(To find t all we do the same thing we did last time except now we subtract 2018 from 2010, which equals 8)

P = 20(8) + 375

P = 160 + 375

<h2>Both our equations agree, and in 2018 there will be 535 wolves.</h2>

The advantage of defining the input variable is that it helps simplify the calculation and makes it more intuitive.

7 0

2 years ago

Circle A and circle B are congruent. CD is a cord of both circles. if AB = 24 inches in the radius is 13 inches how long is CD A

Nitella [24]

Option A

Length of CD is 10 inches

<u><em>Solution:</em></u>

The diagram is attached below

Given that, Circle A and circle B are congruent

CD is a cord of both circles

AB = 24 inches

Radius = 13 inches

To find: length of CD

Draw a straight line connecting A and C

AC represents the radius of circle. Also given that radius is 13 inches, So AC = 13 inches

Given in question that AB = 24 inches

Therefore from figure, AO = AB/2 = 24/2 = 12

AO = 12

Let "b" be the length of CO

Therefore, CD = CO + OD = b + b

AOC forms a triangle, so we can use pythogoras theorem

Pythagorean theorem, states that the square of the length of the hypotenuse is equal to the sum of squares of the lengths of other two sides of the right-angled triangle.

By above definition for triangle AOC

$AC^2 = AO^2 + OC^2$

Substituting AC = 13 and AO = 12 and OC = b

$13^2 = 12^2 + b^2\\\\b^2 = 169 - 144\\\\b^2 = 25\\\\b = 5$

<em><u>Thus length of CD is:</u></em>

CD = b + b = 5 + 5 = 10

Thus length of CD is 10 inches

8 0

3 years ago