A double replacement reaction occurs when the ionic parts of two ionic compounds are exchanged.
Reaction 1 results in a product which is a single compound. No ionic parts are exchanged.
Reaction 3 results in one compound being separated into its elemental parts. No ionic parts are exchanged.
Reaction 4 has two reactants, but Pb is an element and not an ionic compound. No ionic parts are exchanged.
Hence, the answer is Reaction 2. Both NaBr and Ca(OH)2 are ionic compounds. Br - is the anion in NaBr, and (OH)2 is also an anion. Ionic parts are exchanged.
Answer:
V = π r 2h
Step-by-step explanation:
Improper Fraction
12/7 = 1 5/7
The price of one hat is $2 and one pair of mittens is $5
Step-by-step explanation:
Hats and mittens are on sale at the store!
- One woman was able to buy 5 hats and 4 pairs of mittens for $30
- Another woman purchased 3 pairs of mittens and 2 hats for $19
- The price of one hat is x
- The price of one pair of mittens is y
We need to find x and y
∵ One woman was able to buy 5 hats and 4 pairs of mittens for $30
∵ The price of one hat is x
∵ The price of one pair of mittens is y
- Multiply 5 hats by x and 4 pairs of mittens by y and equate
their sum by 30
∴ 5x + 4y = 30 ⇒ (1)
∵ Another woman purchased 3 pairs of mittens and 2 hats for $19
- Multiply 2 hats by x and 3 pairs of mittens by y and equate
their sum by 19
∴ 2x + 3y = 19 ⇒ (2)
Now we have a system of equations to solve it
Multiply equation (1) by -2 and equation (2) by 5 to eliminate x
∵ -10x - 8y = -60 ⇒ (3)
∵ 10x + 15y = 95 ⇒ (4)
- Add equations (3) and (4)
∴ 7y = 35
- Divide both sides by 7
∴ y = 5
Substitute the value of y in equation (1) or (2) to find x
∵ 2x + 3(5) = 19
∴ 2x + 15 = 19
- Subtract 15 from both sides
∴ 2x = 4
- Divide both sides by 2
∴ x = 2
The price of one hat is $2 and one pair of mittens is $5
Learn more:
You can learn more about the system of equations in brainly.com/question/2115716
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The probability any one system works is 0.99
So the probability of any one system failing is 1-0.99 = 0.01, so basically a 1% chance of failure for any one system
Multiply out the value 0.01 with itself four times
0.01*0.01*0.01*0.01 = 0.000 000 01
I'm using spaces to make the number more readable
So the probability of all four systems failing is 0.00000001
Subtract this value from 1 to get
1 - 0.00000001 = 0.99999999
The answer is 0.99999999 which is what we'd expect. The probability of at least one of the systems working is very very close to 1 (aka 100%)
