4x - 5y = 40
4x = 40 + 5y
x = 10 + 5/4y
The x intercept is 10.
Answer:
The amount the school pays is £32.40
Step-by-step explanation:
The cost of each pen = 15 pence
The cost of each ruler = 20 pence
The number of pens bought by the school = 150
The number of rulers bought by the school = 90
The cost reduction (discount) on the items bought = 1/5
Therefore, we have;
The total cost of the pens bought by the school = 150 × 15 = 2250 = £22.50
The total cost of the rulers bought by the school = 90 × 20 = 1800 = £18.00
The total cost of the writing materials (rulers and pens) bought by the school = £22.50 + £18.00 = £40.50
The discount = 1/5 total cost reduction = 1/5×£40.50 = $8.10
The amount the school pays = The total cost of the writing materials - The discount
The amount the school pays = £40.50 - $8.10 = £32.40
The amount the school pays = £32.40.
Answer:
The expected number of tests, E(X) = 6.00
Step-by-step explanation:
Let us denote the number of tests required by X.
In the case of 5 individuals, the possible value of x are 1, if no one has the disease, and 6, if at least one person has the disease.
To find the probability that no one has the disease, we will consider the fact that the selection is independent. Thus, only one test is necessary.
Case 1: P(X=1) = [P (not infected)]⁵
= (0.15 - 0.1)⁵
P(X=1) = 3.125*10⁻⁷
Case 2: P(X=6) = 1- P(X=1)
= 1 - (1 - 0.1)⁵
P(X=6) = (1 - 3.125*10⁻⁷) = 0.999999
P(X=6) = 1.0
We can then use the previously determined values to compute the expected number of tests.
E(X) = ∑x.P(X=x)
= (1).(3.125*10⁻⁷) + 6.(1.0)
E(X) = E(X) = 6.00
Therefore, the expected number of tests, E(X) = 6.00
