How much water must be added to 1 litre of 5% cordial mixture to produce a 4% cordial mixture?
1 answer:
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For this case, we must find an expression equivalent to:
By definition of power properties we have:
Rewriting the previous expression we have:
The "-" are canceled and we take into account that:
So:
According to one of the properties of powers of the same base, we must put the same base and add the exponents:
Answer:
Option B
Answer:
First choice:
Explanation:
<em>The probability that the first is a man's card and the second, a woman's card</em> is calculated as the product of both probabilities, taking into account the fact that the second time the number of cards in the hat has changed.
In spite of it is said that the cards are drawn at once, since it is stated a specific order for the cards (first is a man's card and the second, a woman's card) you can model the procedure as if the cards were drawn consecutively, instead of at once.
<u>1. Probability that the first is a man's card</u>
- Number of cards in the hat = 20 (the 20 business card)
- Number of man's card in the hat: 10
- Probability = favorable oucomes / possible outcomes = 10/20 = 1/2.
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<u>2. Probability that the second is a woman's card</u>
- Number of cards in the hat = 19 (there is one less card in the hat)
- Number of wonan's card in the hat: 10
- Probability = favorable oucomes / possible outcomes = 10/19.
<u>3. Probability that the first is a man's card and the second, a woman's card</u>
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- (1/2) × (10/19) = 5/19
That is the first choice.