Answer:
(a) 
(b) 
Explanation:
Represent losing with L and winning with W.
So:
--- Given

Probability of winning would be:



The question illustrates binomial probability and will be solved using the following binomial expansion;

So:
Solving (a): Winning at least 1
We look at the above and we list out the terms where the powers of W is at least 1; i.e., 1,2,3 and 4
So, we have:

Substitute value for W and L


<em>Hence, the probability of her winning at least one is 0.7599</em>
Solving (a): Wining exactly 2
We look at the above and we list out the terms where the powers of W is exactly 2
So, we have:

Substitute value for W and L


<em>Hence, the probability of her winning exactly two is 0.2646</em>
Answer:
The electron cloud
Explanation:
Metallic bonds result from interaction of positively charged metal ions with free valence electrons which now forms an electron cloud around the metal ions. Electrostatic interaction between the metal ions and the electron cloud holds the metal ions together in the metallic bond.
<span>The amount of heat energy needed to increase the temperature of a substance by </span>

<span> is given by:
</span>

<span>
where m is the mass of the substance, Cs is its specific heat capacity and </span>

<span> is the increase in temperature of the substance.
In this problem, we have a certain mass m of gold, with specific heat capacity </span>

<span>, to which we add Q=2825 J of energy. Its temperature increases by </span>

<span>. Therefore, if we re-arrange the previous equation, we can find the mass of the block of gold:
</span>

<span>
So, the correct answer is B.</span>