WASHINGTON — Just a quarter of this year’s high school graduates who took the ACT tests have the reading, math, English and science skills they need to succeed in college or a career, according to data the testing company released this morning.

The numbers are even worse for black high school graduates: Only 5 percent are fully ready for life after high school.

The results, part of ACT’s annual report, indicate thousands of students graduate from high schools without the knowledge necessary for the next steps in life. The data also show a downturn in overall student scores, although company officials attribute the slide to updated standards and more students taking the exams — including those with no intention of attending two- or four-year colleges.

The ACT report is based on the 54 percent of high school graduates this year who took the exams.

Under ACT’s definition, a young adult is ready to start college or trade school if he has the knowledge to succeed without taking remedial courses. Success is defined as the student’s having a 75 percent chance of earning a C grade and a 50 percent chance of earning a B, based on results on each of the four ACT subject areas, which are measured on a scale from 1 to 36 points.

Only 26 percent of students met the benchmarks for all four sections of the ACT test.