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There are n sweets in a bag, 6 of which are orange, the rest are yellow. Hannah takes a random sweet from the bag and eats it, and then does so again. The probability that Hannah eats two orange sweets is 1/3. Show that n^2-n-90=0.

The probability that the first sweet Hannah eats is orange is 6/n, as there are n sweets and 6 of them are orange. If this is indeed orange, then there are now n-1 sweets left in the bag, of which 5 are oran...
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Answered by Jonny S. • Maths tutor
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What is Osmosis?

The one definition of osmosis is 'The movement of water from a high concentration to a low concentration, down it's concentration gradient, across a partially permible membrane, until osmotic pressue is equa...
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Answered by Alexandra V. • Biology tutor
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Bismuth-208, which has an atomic mass of 208u and 83 protons in the nucleus, decays through the emission of 2 alpha particles and a beta-positive particle. What isotope results from this decay?

208 83 Bi ==> x y Z + 4 2 a + 4 2 a + 0 1 B x = 208 - 8 = 200 y = 83 - 5 = 78 Proton number = 78 therefore Z = Pt Z= 200 78 Pt
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Answered by Danny L. • Physics tutor
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During the redox reaction in glycolysis, which molecule acts as the oxidising agent?

The oxidation of glyceraldehyde 3-phosphate (G3P), a three-carbon sugar, yields energy. In this oxidation, electrons and H+ are transferred to NAD+, forming NADH, and a phosphate group is attached to the oxi...
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Answered by Daniel A. • Biology tutor
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Why is internal temperature regulation an important homeostasis?

Internal temperature of your body must be tighly controlled. The key processes of your body are driven by enzymatic activity and there is an optimal temperature at which these operate. If body temperature in...
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Answered by Archie I. • Biology tutor
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