Table:
0
A
B
C
D
E
F
1
policy id
customer id
policy type code
start date
end date
customer policies
2
119
1
Car
2018-01-21
2017-12-15
3
141
2
Life
2017-08-21
2017-09-29
4
143
3
Car
2017-06-16
2017-12-09
5
218
4
Car
2017-09-18
2017-11-23
6
264
4
Car
2016-12-25
2018-01-25
7
270
5
Life
2016-07-17
2018-01-05
8
352
6
Property
2016-05-23
2017-12-09
9
396
7
Travel
2017-07-30
2017-10-09
10
473
3
Travel
2017-04-24
2017-12-14
11
552
12
Travel
2017-12-13
2017-11-05
12
587
13
Travel
2017-03-23
2017-09-01
13
738
8
Travel
2018-06-16
2017-12-04
14
744
6
Property
2017-12-01
2018-03-07
15
858
9
Property
2016-05-30
2018-02-11
16
900
2
Property
2017-01-20
2017-12-11

Questions and formulas:
Question: Policy type which is used by the highest number of customers.
Formula: TAKE(SORT(SUMMARIZE(C1,SUMX(B1)), 2, -1), 1)
Formula2: TAKE(SORT(SUMMARIZE(C2:C16,SUMX(B2:B16)), 2, -1), 1)
Level: hard
Question: Most popular policy type 
Formula: TAKE(SORT(SUMMARIZE(C1,COUNTX(C1)), 2, -1), 1)
Formula2: TAKE(SORT(SUMMARIZE(C2:C16,COUNTX(C2:C16)), 2, -1), 1)
Level: hard
Question: the policy type used by the most customers.
Formula: TAKE(SORT(SUMMARIZE(C1,SUMX(B1)), 2, -1), 1)
Formula2: TAKE(SORT(SUMMARIZE(C2:C16,SUMX(B2:B16)), 2, -1), 1)
Level: hard
Question: The policy type chosen by most customers.
Formula: TAKE(SORT(SUMMARIZE(C1,SUMX(B1)), 2, -1), 1)
Formula2: TAKE(SORT(SUMMARIZE(C2:C16,SUMX(B2:B16)), 2, -1), 1)
Level: hard