Table:
0
A
B
C
D
E
F
1
Model
PPI (pixels per inch )
ppcm (pixels per cm )
Resolution
Typical viewing distance (in/cm)
Pixels per degree (PPD)
2
iPhone 4 / 4S and iPod Touch (4th generation)
326
128
960×640
inches (cm)
57
3
iPhone 5 / 5S / 5C and iPod Touch (5th generation)
326
128
1136×640
inches (cm)
57
4
iPad ( 3rd / 4th generation / iPad Air )
264
105
2048×1536
inches (cm)
69
5
iPad Mini (2nd generation)
326
128
2048×1536
inches (cm)
85
6
MacBook Pro with Retina Display 15"
220
87
2880×1800
inches (cm)
77

Questions and formulas:
Question: How many different PPI does the model with ppcm of 87 have?
Formula: ROWS(UNIQUE(FILTER(B1, C1=87)))
Formula2: ROWS(UNIQUE(FILTER(B2:B6, C2:C6=87)))
Level: medium
Question: What's the resolution of the model with a PPD of 69?
Formula: LET(query1,SUMMARIZE(D1,SUMX(F1)),FILTER(query1,CHOOSECOLS(query1,2)=69))
Formula2: LET(query1,SUMMARIZE(D2:D6,SUMX(F2:F6)),FILTER(query1,CHOOSECOLS(query1,2)=69))
Level: hard