Answer:
25.2
Step-by-step explanation:
6/5 is 1.2, so it takes 1.2 minutes to run one lap.
This means 21 x 1.2 = the minutes it takes to run 21 laps around the track.
Therefore it takes 25.2 minutes to run around the track 21 times.
The sum of the first four terms of the sequence is 22.
In this question,
The formula of sum of linear sequence is

The sum of the first ten terms of a linear sequence is 145
⇒ 
⇒ 145 = 5 (2a+9d)
⇒ 
⇒ 29 = 2a + 9d ------- (1)
The sum of the next ten term is 445, so the sum of first twenty terms is
⇒ 145 + 445
⇒ 
⇒ 590 = 10 (2a + 19d)
⇒ 
⇒ 59 = 2a + 19d -------- (2)
Now subtract (2) from (1),
⇒ 30 = 10d
⇒ d = 
⇒ d = 3
Substitute d in (1), we get
⇒ 29 = 2a + 9(3)
⇒ 29 = 2a + 27
⇒ 29 - 27 = 2a
⇒ 2 = 2a
⇒ a = 
⇒ a = 1
Thus, sum of first four terms is
⇒ 
⇒ 
⇒ S₄ = 2(2+9)
⇒ S₄ = 2(11)
⇒ S₄ = 22.
Hence we can conclude that the sum of the first four terms of the sequence is 22.
Learn more about sum of sequence of n terms here
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Answer:
62.5 %
Step-by-step explanation:
you have to subtract 32-12, which equals 20
then divide 20 by the original amount (20/32)
20/32= .625, then you have to multiply to get the final answer...hope this helped!