Answer:
53
Step-by-step explanation:
When I entered 53 into PLATO, it appears to be the correct answer.
The formula for the sum of an arithmetic series is expressed as:
Sn=n/2(a1+an)
where:
n=total terms
a1=the initial term
an=the final term
given
n=18, an=275, Sn=4185
substituting these values into the equation results in:
4185=18/2(a1+275)
after simplification, we obtain:
4185=9(a1+275)
dividing by 9 yields:
465=a1+275
therefore
a1=465-275
a1=190
Conclusion: the first term is 190
Adam and his dad split the bill in a 2:3 ratio. The dad’s share equals the 3 parts and is £52.20, so one part is 52.20 ÷ 3 = £17.40. Adam’s portion (2 parts) is 2 × 17.40 = £34.80. The total cost is 34.80 + 52.20 = £87.00.
There are 2 beginner, 6 intermediate, and 3 advanced books, totaling 11.
P(advanced) = 3/11
replaced
P(beginner) = 2/11
P(both) = 3/11 * 2/11 = 6/121 <=