1.. a telegraph has a number of arms and each arm is capable of  taking 4 different positions, including the position of rest. if 1023 different signalscan be sent in all. find the no. of arms?.. (i didn't even understood the question)

2...in how many ways 6 boys and 4 girls sit in a row so that no boy is between 2 girls??

3....inhow many ways can the letter of the word ALGEBRA be arranged without changing the relative order of vowels and consonents?

(please please post a detailed solution)