Master Letter writing Part 3 in 45 min

A substance disintegrated 87.5% in 45 min. What is it half-life?

How to Write a Letter to The Editor|Letter Writing Format|Question|Complain Letter

How to Write a Letter to The Editor|Letter Writing Format|Question|Complain Letter

How to Write a Letter to The Editor|Letter Writing Format|Question|Complain Letter

Find the ratio of 4 min: 45 sec

Letter: Format|Introduction|Parts Of A Letter - A Letter Consists Of Six Different Part:|Salutation & Greeting|Questions|Letter To Editor|Summary

Letter: Format|Introduction|Parts Of A Letter - A Letter Consists Of Six Different Part:|Salutation & Greeting|Questions|Letter To Editor|Summary

3 letters are to be posted in 5 letter boxes in a part of the town .IF all letters are not posted in the same letter box . The number of ways of posting is

If the letters of the word MASTER are permuted in all possible ways and the words thus formed are arranged in the dictionary order, then find the ranks of the words i) REMAST ii) MASTER

Are the set A={b,c,d,e} and B={x:x " is a letter in the word 'MASTER'"} joint?