What would be the expected probability of making at least one Type I error when conducting twenty tests?

Question

The full question is:

If you ran 20 independent tests on the correlation between dataset1 and each of set A to T using an alpha of 5% what would be the expected familywise error rate? i.e. What would be the expected probability of making at least one Type 1 error when conducting twenty tests?

dataset1 = 13, 15, 2, 5, 19, 11, 2, 7, 19, 10

datasets A to T =

datasetA = 13,14,18,20,4,10,14,13,10,9

> datasetB = 5,15,11,2,2,10,2,20,6,10

> datasetC = 6,2,20,18,6,4,10,8,18,2

> datasetD = 1,2,19,17,12,11,11,11,13,18

> datasetE = 8,13,4,19,18,5,6,11,19,17

> datasetF = 13,14,4,5,16,12,7,15,18,3

> datasetG = 10,13,2,5,11,8,14,4,7,17

> datasetH = 11,15,5,4,19,11,3,5,16,9

> datasetI = 13,5,20,5,6,11,18,5,9,15

> datasetJ = 12,11,5,18,5,3,4,6,5,13

> datasetK = 16,19,6,13,17,19,18,15,10,9

> datasetL = 2,1,8,8,15,13,6,18,12,4

> datasetM = 18,9,2,10,19,14,11,15,9,5

> datasetN = 2,12,17,6,4,15,1,16,17,16

> datasetO = 13,2,9,5,6,17,20,5,9,17

> datasetP = 5,13,19,17,12,9,6,7,9,12

> datasetQ = 1,12,6,11,11,18,10,3,8,14

> datasetR = 12,18,18,17,10,17,14,3,19,2

> datasetS = 18,16,10,14,13,18,8,15,3,11

> datasetT = 9,13,14,6,17,19,7,9,7,7

Answer 1

P(at least 1 type I error in 20 tests) = 1 - P(no type 1 error in 20 tests)