2.261 agreement with verb

When you talk about fractions of a single thing, you use a singular form of a verb afterwards.

• Half of our work is to design programmes.
• Two thirds of the planet's surface is covered with water.
• Two fifths of the forest was removed.

However, when you talk about fractions of a number of things, you use a plural form of a verb afterwards.

• Two thirds of Chad's exports were cotton.
• A quarter of the students were seen individually.