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3 years ago

13

On the shelves of Maria's bookcase,1/2 of the books are mysteries,1/10 are science fiction, 1/5 are biographies,and the remainin

g 4 are classics.How many books are in her bookcase?

1 answer:

PolarNik [594]3 years ago

7 0

There are 12 books in her bookcase

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Solve the equations<br> 7 x = 21<br> 2/3 = 5/6

S_A_V [24]

Answer:

x = 3??

Step-by-step explanation:

4 0

3 years ago

Seven pieces of rope have an average (arithmetic mean) length of 68 centimeters and a median length of 84 centimeters. If the le

Svet_ta [14]

Answer:

The maximum possible length, in centimeters, of the longest piece of rope is 134 cm

Step-by-step explanation:

Let the seven pieces be a,b,c,d,e,f,g

Average of 7 pieces of ropes =68

$Average = \frac{\text{Sum of all lengths}}{\text{No. of pieces}}$

$68= \frac{\text{Sum of all lengths}}{7}$

$68 \times 7 =\text{a+b+c+d+e+f+g}$

$476=\text{a+b+c+d+e+f+g}$ --A

We are given that the median length of a piece of rope is 84 centimeters.

We arrange the pieces in the ascending order

So, median will be the length of 4th piece

So, d = 84 cm

the length of piece a,b,c will be less than 84 and the value of e,f,g must be greater than or equal to 84

Let us suppose the length of a,b,c be x

Let us suppose the length of e,f be 84

The length of the longest piece of rope is 14 centimeters more than 4 times the length of the shortest piece of rope

So, g = 4x+14

Substitute the value in A

$476=x+x+x+84+84+84+4x+14$

$476=7x+266$

$\frac{476-266}{7}=x$

$30=x$

g = 4x+14=4(30)+14=134

Hence the maximum possible length, in centimeters, of the longest piece of rope is 134 cm

7 0

3 years ago

The mean breaking strength of yarn used in manufacturing drapery material is required to be more than 100 psi. Past experience h

Ganezh [65]

Answer:

H0: μ = 100 ; H1: μ > 100 ;

Test statistic = 0.75 ;

We fail to reject null ;

Kindly check explanation for the rest

Step-by-step explanation:

Given that :

H0: μ = 100

H1: μ > 100

Sample mean, x = 100.6 ; n = 9 ; sample Standard deviation, s = 2.4

Test statistic :

(x - μ) ÷ s/sqrt(n)

(100.6 - 100) ÷ 2.4 / sqrt(9)

0.6 ÷ 0.8 = 0.75

Probability of not rejecting the null :

P = P(Z > 0.75) = 0.22663

α = 0.05

Since, P > α ; we fail to reject the Null ; there is no sufficient evidence to accept the claim that mean strength is > 100 psi

μ + Zcritical*s/sqrt(n)

Zcritical at (1 - α) = 1.645

100 + 1.645*(2.4/3)

100 + 1.316 = 101.316

(x - μ) ÷ s/sqrt(n)

(101.316 - 102) ÷ 2.4 / sqrt(9)

-0.684 ÷ 0.8 = 0.75

= - 0.855

P(Z < - 0.855) = 0.1963 (Z probability calculator).

95% lower confidence interval :

x - error margin, E

E = Zcritical * s/sqrt(n)

E = 1.645 * 0.8 = 1.316

100.6 - 1.316 = 99.284

From part c :

Interval becomes ;

(99.284, 101.316) ; this interval contains the hypothesized mean value of 100. Hence we fail to reject the null.

8 0

3 years ago

A prism is completely filled with 96 cubes that have edge length of 1/2 cm.

ch4aika [34]

I know this is kinda late, but...

You can solve this easily as long as you remember how to find the volume of a cube. v=a^3, when a means length. The length is 1/2 cm, or .5 cm.
So, v+.5^3, which equals .125 cm. Each cube has a that volume. Now, multiply that by how many actual cubes there are, 96.

96 * .125 = 12

8 0

3 years ago

Read 2 more answers

A square pyramid has a base side length of 8 feet. The height of each lateral face is 12 feet. What is the surface area of the p

iragen [17]

I am not sure but answer can be 1,5 or 96 and ir Can be wrong but ı am trying to help you

3 0

3 years ago