We have,
Percentage of sand in mortar = 55%
Percentage of cement in mortar = 33%
So, percentage of lime in mortar = 100 – 55 – 33
= 100 – 88
= 12%
∴ Weight of mortar = 800 kg
∴ Mass of lime in mortar = 12% of 800 kg
= 12/100 x 800
= 12 x 8
= 96 kg
Hence, weight of lime in mortar is 96 kg.