What is a placebo and why is it important in an experiment to test the effectiveness of a drug
1 answer:
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Let x% be the salt concentration of first solution.
Then in 8ml, amount of salt =
Given that to this 8ml solution, 11ml solution of a 47% salt solution is mixed.
amount of salt in 11ml of 47% salt solution is =
So, total amount of salt in new mixture =
But given that this new solution is a 43% salt solution.
Hence amount of salt in new mixture of (8+11)=19ml solution of 43% salt solution is
Hence
8x+517 = 817
8x=817-517 = 300
x= 300/8 = 37.5
Hence the salt concentration in the first solution is 37.5%
Answer: Option (A)
Step-by-step explanation:
Let the original price of the clock be "x "
<em>The clock is then resold to a collector = x + 20% of "x "</em>
<em>= x + 0.2x</em>
<em>= 1.2x</em>
Now, the shop re-buy the clock at a price = <em></em>
<em></em>
<em>= 0.6x </em>
Therefore,
<em>Original Cost - Buy-Back price = $100</em>
<em>⇒ x - 0.6x = 100</em>
<em>⇒ x = 250 </em>
Hence , the selling price of the clock for the second time is
<em></em>
<em>= $270 </em>
<em></em>