A collection of dimes and nickels has a value of 1.65. if there are 20 coins in all how many of the coins are dimes?

Mathematics

1 answer:

Nostrana [21]3 years ago

3 0

This question gives you information to make a system of equations, which you then use substitution to solve.

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Meteorologists in Texas want to increase the amount of rain delivered by thunderheads by seeding the clouds. Without seeding, th

Dafna11 [192]

Answer:

There is no significant difference in the amount of rain produced when seeding the clouds.

Step-by-step explanation:

Assuming that the amount of rain delivered by thunderheads follows a distribution close to a normal one, we can formulate a hypothesis z-test:

Null Hypothesis

$\bf H_0$ : Average of the amount of rain delivered by thunderheads without seeding the clouds = 300 acrefeet.

Alternative Hypothesis

$\bf H_a$ : Average of the amount of rain delivered by thunderheads by seeding the clouds > 300 acrefeet.

This is a right-tailed test.

Our z-statistic is

$\bf z=\frac{370.4-300}{300.1/\sqrt{30}}=1.2845$

We now compare this value with the z-critical for a 0.05 significance level. This is a value $\bf z^*$ such that the area under the Normal curve to the left of $\bf z^*$ is less than or equal to 0.05

We can find this value with tables, calculators or spreadsheets.

In Excel or OpenOffice Calc use the function

NORMSINV(0.95)

an we obtain a value of

$\bf z^*$ = 1.645

Since 1.2845 is not greater than 1.645 we cannot reject the null, so the conclusion that can be drawn when the significance level is 0.05 is that there is no significant difference in the amount of rain produced when seeding the clouds.

8 0

3 years ago

Drag the correct symbol into the box to compare the expressions. 62–22 4(6 + 2)

jeyben [28]

Its A = If you want to know how I did it subtract 62-22 then what ever you get multiply it by 4 then Carry on from their

5 0

3 years ago

Read 2 more answers

What is the value of (2x^2-5x+4)if x =7

Troyanec [42]

We have to use PEMDAS for this expression.

Parentheses
Exponents
Multiplication
Division
Addition
Subtraction

(2x^2 - 5x + 4) Original Mathematical Expression

[2(7)^2 - 5(7) + 4] Plugging the value of x, 7 into expression.

There are parentheses, so that means we have to work in them.

There are exponents, so we have to do those first.

[2(49) - 5(7) +4] Exponents.

There is multiplication, that we can do, so we do that left to right.

[98 - 35 + 4] Multiplication.

There is no division.

There is addition and subtraction, so we do those left to right.

[63 + 4] Subtraction.

67 Addition.

Final Answer: 67

6 0

3 years ago

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What value of x makes the equation true 4x = 32?

pochemuha

Answer:

$x=8$