To find b1, we need to use the formula for calculating the sum of the first n terms of an arithmetic series:
S(n) = n/2 * (a1 + an)
Given that S4 = 909 and the common difference g = 10, we know that n = 4 and an = a1 + 3g.
Substitute the values into the formula:
909 = 4/2 (a1 + a1 + 3g909 = 2 (2a1 + 30909 = 4a1 + 6849 = 4aa1 = 849 / a1 = 212.25
Therefore, b1 = 212.25.
To find b1, we need to use the formula for calculating the sum of the first n terms of an arithmetic series:
S(n) = n/2 * (a1 + an)
Given that S4 = 909 and the common difference g = 10, we know that n = 4 and an = a1 + 3g.
Substitute the values into the formula:
909 = 4/2 (a1 + a1 + 3g
909 = 2 (2a1 + 30
909 = 4a1 + 6
849 = 4a
a1 = 849 /
a1 = 212.25
Therefore, b1 = 212.25.