Hello! I need help with a question I missed on my practice STAT final exam. Would love the step-do-step on how to solve so I do better on the actual exam. Thank you!

Q: An economist is testing the claim that the proportion of people in the population who visit the dentist twice a year in Mexico is 0.20. Based on a random sample of 500 people, he finds that the sample proportion is 0.10. What is the z test statistic assuming the standard deviation in the population is 0.50 (round your answer to two decimal places)?

Note: I thought the answer was -0.20 but apparently it is -4.47

Can anyone help me solve this? Is it STDEV/SQRT(sample) so .5/(SQRT(500)

Which comes out to .00447... so is anything below 1 a negative number? How do I get to -4.47 from .0047...I am confused!

Call : 1m(formula = Murder ~ Assault, data = USArrests) Residuals : Min 1Q Median 3Q Max -4.8528 -1. 7456 -0. 3979 1. 3044 7.9256 coefficients : Estimate Std. Error t value Pr(>|t|) (Intercept) 0. 631683 0. 854776 0. 739 0. 464 Assault 0 . 041909 0. 004507 9. 298 2.6e-12 Signif. codes: 0 '***' 0.001 '*' 0.01 "#' 0.05 '.' 0.1 ' '1 Residual standard error: 2.629 on 48 degrees of freedom Multiple R-squared: 0. 643, Adjusted R-squared: 0. 6356 F-statistic: 86.45 on 1 and 48 DF, p-value: 2. 596e-12