Final answer:
The number of male pupils in San Jose Elementary School is 99 when the ratio of male to female pupils is 7:9, and there are 128 female pupils.
Step-by-step explanation:
The question involves finding out the number of male pupils in San Jose Elementary School when the ratio of male to female pupils is given as 7:9, and the number of female pupils is 128.
To find out the number of males, we can set up a proportion using the ratio and solve for the number of males (M).
7 males / 9 females = M males / 128 females
By cross-multiplying and solving for M:
7 females × 128 males = 9 males × M females
M = (7 × 128) / 9
M = 896 / 9
M = 99.555...
Since the number of students can't be a fraction, we round down to the nearest whole number:
M = 99 males
Therefore, there are 99 male pupils in San Jose Elementary School.