We know that,
[tex] \rightarrow \: z = \frac{x - \mu}{\sigma} \\ [/tex]
inserting the given values in the formula
[tex]\rightarrow \: z = \frac{27.87 - 30}{1.9} \\\rightarrow \: z = - 1.121[/tex]
Area that's left to z = -1.121
Area that's left to -1.121 = 0.1311
= 13.11%
Hence ,
13.11% of the watermelons weigh less than 27.87 pounds
To find the number of watermelons,
We'll find 13.11% of 400
= 13.11% x 400
= 13.11/100 x 400
= 52.44
hence , approx 52 watermelons would be lesser than 27.87 pounds