Remember: We have to work from either the LHS or the RHS.
(Left hand side or the Right hand side)
You should already know this:

You should also know this:

So plugging in both of those into our identity, we get:

Simplify the denominator on the LHS (Left Hand Side)
We get:

LHS = RHS
Therefore, identity is verified.
For 1. To estimate how many sports cards Alberto had, you would round each number to the nearest ten, so 318 would become 320. 273 would then become 270. You would then add those two and would get 590. So, Alberto had 590 sports cards (estimated). If you were looking for the actual answer (not estimated) , you would get 591.
This question is incomplete, the complete question is;
In a survey, 55% of the voters support a particular referendum. If 40 voters are chosen at random,
find the mean and variance for the number of voters who support the referendum.
Answer:
a) The Mean is 22
b) Variance is 9.9
Step-by-step explanation:
Given that;
55% of the voters support a particular referendum p = 0.55
q = 1 - p = 1 - 0.55 = 0.45
sample size n = 40
a)
Mean = sample size n × p
Mean = 40 × 0.55
Mean = 22
Therefore the Mean is 22
b)
Variance = n × p × q
so we substitute
Variance = 40 × 0.55 × 0.45
Variance = 9.9
Therefore the Variance is 9.9
Alternate interior angles are equal.
2x - 10 = 65 - x
2x + x = 65 + 10
3x = 75
x = 75/3 = 25
x = 25.