Answer:

Step-by-step explanation:
Ask yourself, when will Xavier and Yolanda meet??
Firstly, since it is given that Xavier doesn't wait at all, in order for them to meet, Yolanda must arrive before Xavier. This in mathematical terms can be expressed as

Secondly, Yolanda will wait for only 45 minutes, So Xavier must arrive before that, i.e

Combining both conditions, we obtain

If
and
be the density functions for Xavier and Yolanda respectively, the probability of meeting is given by,
.