The mean weight (in kg) of four students is 30. The weights of three of them are 42 kg, 28 kg, and 24 kg. What is the weight (in kg) of the fourth student?

Let the weight of the fourth student be x kg.
Given that the mean weight of 4 students is 30 kg:

Total weight of 4 students=4×30=120 kg
The sum of the weights of the given three students is:

Sum=42+28+24=94 kg
Therefore, the weight of the fourth student is:

x=120−94=26 kg