<prompt> Out of 10 relatives exposed to a primary case, of measles, 6 developed measles. Secondary attack rate of measles-10-Apr10-Jun6-Apr4-Jun  <response>: Ans. is b i.e., 610 Secondary attack rate SARo SAR is defined as the number ofexposed persons developing the disease within the range of incubation period, following exposure to primary caseSARNo of exposed persons developing disease withinthe range of the incubation period---Total number of exposedsusceptible contactx 100 SAR 610x 100 