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sdas [7]
3 years ago
12

Red and grey bricks were used to build a decorative wall. The number of red bricks/number of grey bricks was 5/2 There were 140

bricks used in all. How many red bricks were used?
Mathematics
1 answer:
ehidna [41]3 years ago
5 0

5/2 = 5:2

Lets take 5:2 as 5x and 2x.

5x + 2x = 140

7x = 140

x = 140/7

x = 20

So, 5x = 5x20 = 100 red bricks

and, 2x = 2x20 = 40 grey bricks.

100 + 40 = 140 bricks

So, to build the decorative wall, 100 red bricks and 40 grey bricks were used.

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Several years​ ago, 38​% of parents who had children in grades​ K-12 were satisfied with the quality of education the students r
Colt1911 [192]

Answer:

0.428 - 1.96\sqrt{\frac{0.428(1-0.428)}{1165}}=0.3995

0.428 + 1.96\sqrt{\frac{0.428(1-0.428)}{1165}}=0.4564

We are confident that the true proportion of people satisfied with the quality of education the students receive is between (0.3995, 0.4564), since the lower value for this confidence level is higher than 0.38 we have enough evidence to conclude that the parents' attitudes toward the quality of education have changed.

Step-by-step explanation:

For this case we are interesting in the parameter of the true proportion of people satisfied with the quality of education the students receive

The confidence level is given 95%, the significance level would be given by \alpha=1-0.95=0.05 and \alpha/2 =0.025. And the critical values are:

z_{\alpha/2}=-1.96, z_{1-\alpha/2}=1.96

The estimated proportion of people satisfied with the quality of education the students receive is given by:

\hat p =\frac{499}{1165}= 0.428

The confidence interval for the proportion if interest is given by the following formula:  

\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}

And replacing the info given we got:

0.428 - 1.96\sqrt{\frac{0.428(1-0.428)}{1165}}=0.3995

0.428 + 1.96\sqrt{\frac{0.428(1-0.428)}{1165}}=0.4564

We are confident that the true proportion of people satisfied with the quality of education the students receive is between (0.3995, 0.4564), since the lower value for this confidence level is higher than 0.38 we have enough evidence to conclude that the parents' attitudes toward the quality of education have changed.

8 0
3 years ago
Can someone please help me answer this
Alexus [3.1K]

Answer:

1) a = 1.6          2) f = 0.53

Step-by-step explanation:

1) 6a = 10                      2) 48 = 90f

6a/6 = 10/6                       90f/90 = 48/90

a = 1.6                                f = 0.53

sorry i could only do the first two, i think those are right

8 0
3 years ago
12 minus b=-2 solve for b
ycow [4]
12 - b = -2
12 + 2 = b
14 = b
5 0
3 years ago
Read 2 more answers
PLEASE HELPPP
iVinArrow [24]

Answer:

The electricity is $500 and the rent is $650.

Step-by-step explanation: I think you just subtract 650 from 1150.

3 0
3 years ago
What is the value of x in the figure?
Bumek [7]

Answer:

29

Step-by-step explanation:

x+61=90

This is because they are complementary angles.

You can tell by the little square in the corner next to them

x=29

4 0
3 years ago
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