Final answer:
The greatest whole number of crates that can be lifted without breaking the crane's cable with a breaking strain of 6400 kg, when each crate weighs 90 kg, is 71 crates.
Step-by-step explanation:
The greatest number of crates that can safely be lifted by the crane without breaking the cable can be calculated using the given breaking strain of the cable, which is 6400 kg. Since each crate weighs 90 kg, you can determine the maximum number of crates by dividing the breaking strain by the weight of one crate.
To find the maximum number of crates, we perform the following calculation:
- Breaking strain of the cable = 6400 kg
- Weight of one crate = 90 kg
- 6400 kg / 90 kg/crate = 71.11 crates
Since you cannot lift a fraction of a crate, the greatest whole number of crates that can be lifted is 71 crates.