Lets suppose there are 30 boxes in total.
We can make a matrix based on the type of boxes: Fragile(F) & Non-Fragile(NF) and their contents, Electronics(E), and Not Electronics (NE).
to find : if total Fragile boxes are T, is E&F >0.5T ?
(1) Two-thirds of the boxes in the shipment are fragile.
Now we know T = 2/3*30 = 20
But we still do not know anything about number of boxes with electronics and if E&F is more than 10.
Statement 1 is insufficient
(2) Four-fifths of the boxes in the shipment contain electronics.
From statement 2:
But we do not know anything about number of fragile boxes (T)
Statement 2 is insufficient
Statement 1 and 2:
| F | NF | |
| E | >10? Min= 14 | | 24 |
| NE | Max = 6 | | 6 |
| 20 | 10 | 30 |
Now we know total Fragile boxes = 20, and total boxes with electronics = 24.
To find the least number of boxes with E&F, we can maximise NE&F= 6
Then E&F= 20 - NE&F = 14
So at minimum. E&F will be 14 which is more than 10(1/2 of total fragile boxes)
so 1 and 2 together are sufficient