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3 years ago

Pls help for brainlist

Mathematics

2 answers:

Flauer [41]3 years ago

4 0

Answer:

15/20-8/20=7/20

Step-by-step explanation:

3/4-2/5 = 15/20-8/20 so

snow_tiger [21]3 years ago

3 0

Answer: 7/20

Step-by-step explanation:

3/4 - 2/5

= 3x5/4x5 - 2x4/5x4

=15/20 - 8/20

= 7/20

Hope it helped u,

pls mark as the brainliest

^_^

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Sami leave his house at 3:45 PM and walks to karlas house in 15 minutes he stays at karlas house for five minutes and then walks

chubhunter [2.5K]

Sami arrives at the library at 4:15. Why? Well is says she took 15 minutes to walk to karlas house so when she arrives it’s 4:00 PM. Than, she stays at karlas house for 5 minutes which puts her at 4:05 PM. After that is Sami took 10 minutes to get to the library so that puts Sami at 4:15 PM. Hope this helps!

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3 years ago

There are 10 marbles in a bag. 1/5 are red and the others are blue. What is the ratio to blue marbles.

Irina-Kira [14]

Answer:

Ratio = 1 : 4

Step-by-step explanation:

Total marbles = 10

Given 1/5 is red, that is 1/5 of the total marbles are red

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Therefore , 10 - 2 = 8 marbles are blue.

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4 0

3 years ago

A physicist examines 25 water samples for nitrate concentration. The mean nitrate concentration for the sample data is 0.165 cc/

xz_007 [3.2K]

Answer:

The 80% confidence interval for the the population mean nitrate concentration is (0.144, 0.186).

Critical value t=1.318

Step-by-step explanation:

We have to calculate a 80% confidence interval for the mean.

The population standard deviation is not known, so we have to estimate it from the sample standard deviation and use a t-students distribution to calculate the critical value.

The sample mean is M=0.165.

The sample size is N=25.

When σ is not known, s divided by the square root of N is used as an estimate of σM:

$s_M=\dfrac{s}{\sqrt{N}}=\dfrac{0.078}{\sqrt{25}}=\dfrac{0.078}{5}=0.016$

The degrees of freedom for this sample size are:

$df=n-1=25-1=24$

The t-value for a 80% confidence interval and 24 degrees of freedom is t=1.318.

The margin of error (MOE) can be calculated as:

$MOE=t\cdot s_M=1.318 \cdot 0.016=0.021$

Then, the lower and upper bounds of the confidence interval are:

$LL=M-t \cdot s_M = 0.165-0.021=0.144\\\\UL=M+t \cdot s_M = 0.165+0.021=0.186$

The 80% confidence interval for the population mean nitrate concentration is (0.144, 0.186).

6 0

3 years ago

Please answer in the next 20 minutes.

oee [108]

Answer:

Matt should have divided 3 by 3, not 24 by 3

Step-by-step explanation:

The mouse traveled 1/24 of a mile every hour so after 3 hours it traveled 3/24 of a mile.

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3 years ago

How would I find all real solutions in x^4/3 -10^2/3 +21= 0

Oxana [17]

Answer:

Step-by-step explanation:

This equation looks complicated.We have to make it easier

let's say x^2/3 = t and x^4/3 = t^2

t^2-10t+21=0 [ we can factorize this equation as a (t-3)(t-7) ]

(t-3)(t-7)=0 [ that means , t can be 3 or 7 ]

But don't forget we have to find x not t so,

t=x^2/3=3 ∛ x^2 = 3 x^2 = 9 x=3 or x= -3

t=x^2/3=7 ∛x^2 = 7 x^2 = 343 x ~18.5 or x ~ -18.5

7 0

2 years ago