1/10, 3/20, 5/30, 7/40 arithmetic sequence geometric sequence neither

If a, b, c is an arithmetic sequence then a + c = 2b

a = 1/10; b = 3/20, c = 5/30

a + c = 1/10 + 5/30 = 3/30 + 5/30 = (3+5)/30 = 8/30
2b = 2 · 3/20 = 3/10 = 9/30

8/30 ≠ 9/30

If a, b, c is a geometric sequence then ac = b²

ac = 1/10 · 5/30 = 1/2 · 1/30 = 1/60
b² = (3/20)² = 9/400

1/60 ≠ 9/400

Neither.

Mike has a choice of an account that compounds daily and an account that compounds monthly. If they both have the same interest rate, which will earn more interest?

Account that is being compounded on a daily basis will earn more interest. This is because in simple words, one is getting some interest on a daily basis and one will yield an 'interest on interest'. Whereas in a monthly compounded account Mike will earn less interest.