Pls help due in like 10 mins- no mfkn links pls pls pls no need to explain
2 answers:
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Answer:
S₁₅ = 645
Step-by-step explanation:
The sum to n terms of an arithmetic sequence is
=
[ 2a₁ + (n - 1)d ]
where a₁ is the first term and d the common difference
Using the nth term formula = 5n + 3 , then
a₁ = 5(1) + 3 = 5 + 3 = 8
a₂ = 5(2) + 3 = 10 + 3 = 13 , then
d = a₂ - a₁ = 13 - 8 = 5
Thus
S₁₅ = [ (2 × 8) + (14 × 5) ]
= 7.5( 16 + 70)
= 7.5 × 86
= 645
Answer: The answer is 400 blue marbles.
Step-by-step explanation: Given that there are 560 marbles in a bag, out of which 65% are red and rest are blue.
So, number of red marbles is
and number of blue marbles is
Now, if 28 red marbles are replaced by blue marbles, the the new number of red and blue marbles will be
Now, to get 65% of the marbles blue, we need to add some more blue marbles to the bag. Let 'x' number of blue marbles are added to the bag, then
Thus, 400 blue marbles need to be added to the bag.