Convert 9.8 × 10^-1 to standard form

Which one ? is the answer and how to find this answer

In a class, there are 12 girls. if the ratio of boys to girls is 5: 4 how many boys are there in the class

Afactory buys 10% of its components from suppliers b and the rest from supplier c. it is known that 6% of the components it buys are faulty. of the components brought from suppliers a,9% are faulty and of the components bought from suppliers b, 3% are faulty. find the percentage of components bought from supplier c that are faulty.