The complete question in the attached figure
we know that
find the square of the speeds of individual particles
2.8²----> 7.84
3.2²---->10.24
5.8²----> 33.64
7.3²----> 53.29
7.4²---> 54.76
average=[7.84+10.24+33.64+53.29+54.76]/5-----> 159.77/5----> 31.954
step 2
find the square root of the average
√31.954=5.65
therefore
the answer is
the option b) 5.7 m/s
we know that
the root mean square speed, is the square root of the average (mean) of all of the square of the speeds of individual particles in a gas.
step 1find the square of the speeds of individual particles
2.8²----> 7.84
3.2²---->10.24
5.8²----> 33.64
7.3²----> 53.29
7.4²---> 54.76
average=[7.84+10.24+33.64+53.29+54.76]/5-----> 159.77/5----> 31.954
step 2
find the square root of the average
√31.954=5.65
therefore
the answer is
the option b) 5.7 m/s