A particle on a stretched string supporting a travelling wave ,takes 5 ms to move from its mean position to extreme position.The distance bw two consecutive particles,which are at their mean positions,is 2 cm.How to find frequency?

hey if you are telling that ,, it takes 5ms to move from mean position to extreme position then  then this time is equal to 1/4th of the total time period so get time period and take it inverse to find frequency,, i don get what is need of the other part ,( which gives the value of wavelength)

right sir.....other part it asked to find wavelength only