Table:
0
A
B
C
D
E
F
G
H
1
transaction id
investor id
transaction type code
date of transaction
amount of transaction
share count
other details
2
1
6
SALE
1988-09-16 19:02:51
302507.6996
8718572
3
2
18
PUR
1982-06-06 17:19:00
27.257
9
4
3
2
SALE
1979-04-27 06:03:59
48777.969
8580
5
4
14
PUR
2001-11-28 15:06:25
4.5263
8040
6
5
8
PUR
1977-08-17 13:13:30
0.0
930
7
6
19
PUR
1985-10-08 13:13:39
207484122.2796
2751
8
7
7
PUR
1990-12-02 09:03:38
822.803
1522
9
8
17
SALE
2004-01-18 20:37:50
78035671.4424
96178
10
9
20
PUR
1977-08-13 02:18:47
82057.207
11
10
2
SALE
1981-01-28 08:07:03
29.3534
1654756
12
11
3
SALE
2000-04-03 20:55:43
0.0
674529892
13
12
18
SALE
1983-11-01 17:57:27
1.0
587
14
13
3
SALE
2002-04-07 20:28:37
183.2
15
14
3
PUR
2002-09-13 03:04:56
0.0
630021
16
15
19
PUR
1997-12-30 05:05:40
8.9
93191

Questions and formulas:
Question: Lowest pur transaction amount with share count over 50.
Formula: MIN(FILTER(E1, (F1>50)*(C1="pur")))
Formula2: MIN(FILTER(E2:E16, (F2:F16>50)*(C2:C16="pur")))
Level: easy
Question: The number of transaction types under each transaction id
Formula: SUMMARIZE(A1,DCOUNTX(C1))
Formula2: SUMMARIZE(A2:A16,DCOUNTX(C2:C16))
Level: easy
Question: The average share count of transactions for all investors.
Formula: SUMMARIZE(HSTACK(B1,A1),AVERAGEX(F1))
Formula2: SUMMARIZE(HSTACK(B2:B16,A2:A16),AVERAGEX(F2:F16))
Level: medium
Question: The average amount of transactions among investors.
Formula: SUMMARIZE(B1,AVERAGEX(E1))
Formula2: SUMMARIZE(B2:B16,AVERAGEX(E2:E16))
Level: easy
Question: Investors with sale transactions
Formula: LET(query1,FILTER(A1:H1,C1="sale"),UNIQUE(CHOOSECOLS(query1,2,1)))
Formula2: LET(query1,FILTER(A2:H16,C2:C16="sale"),UNIQUE(CHOOSECOLS(query1,2,1)))
Level: hard
Question: How many transactions did each investor complete?
Formula: SUMMARIZE(B1,SUMX(A1))
Formula2: SUMMARIZE(B2:B16,SUMX(A2:A16))
Level: easy
Question: Highest amount of transactions
Formula: MAX(E1)
Formula2: MAX(E2:E16)
Level: easy
Question: The total share of transactions.
Formula: SUMMARIZE(A1,SUMX(F1))
Formula2: SUMMARIZE(A2:A16,SUMX(F2:F16))
Level: easy
Question: The ids of pur transactions.
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:H1,C1="pur"),1))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:H16,C2:C16="pur"),1))
Level: medium
Question: sale transaction dates
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:H1,C1="sale"),4))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:H16,C2:C16="sale"),4))
Level: medium
Question: Average sale amount of transaction 
Formula: AVERAGEIFS(E1,C1,"sale")
Formula2: AVERAGEIFS(E2:E16,C2:C16,"sale")
Level: easy
Question: The greatest amount of transaction.
Formula: MAX(E1)
Formula2: MAX(E2:E16)
Level: easy
Question: The dates when sale transaction happened 
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:H1,C1="sale"),4))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:H16,C2:C16="sale"),4))
Level: medium
Question: The least amount of pur transaction with share count over 50.
Formula: MIN(FILTER(E1, (F1>50)*(C1="pur")))
Formula2: MIN(FILTER(E2:E16, (F2:F16>50)*(C2:C16="pur")))
Level: easy
Question: The investor having sale transaction.
Formula: LET(query1,FILTER(A1:H1,C1="sale"),UNIQUE(CHOOSECOLS(query1,2,1)))
Formula2: LET(query1,FILTER(A2:H16,C2:C16="sale"),UNIQUE(CHOOSECOLS(query1,2,1)))
Level: hard
Question: How many transactions did each investor realize?
Formula: SUMMARIZE(B1,SUMX(A1))
Formula2: SUMMARIZE(B2:B16,SUMX(A2:A16))
Level: easy
Question: What is the average amount of sale transactions?
Formula: AVERAGEIFS(E1,C1,"sale")
Formula2: AVERAGEIFS(E2:E16,C2:C16,"sale")
Level: easy